Every MLB Team's Potential Breakout Star in 2019
Whether you favor Mike Trout, Mookie Betts, Francisco Lindor or someone else, you know who the big stars are in Major League Baseball. And good news! They'll be there again in 2019.
But this isn't about them. It's about the next wave of stars about to crash over MLB.
We've pinpointed one potential breakout player for each of MLB's 30 teams. These are guys who haven't been All-Stars or major award winners. They otherwise fit a wide variety of descriptions—prospect, former prospect, heretofore serviceable veteran, etc.—but what ties them together is talent that hasn't yet peaked.
We'll go in alphabetical order by city.
Arizona Diamondbacks: Ketel Marte, INF/OF
With Paul Goldschmidt gone, the Arizona Diamondbacks will need a new leader for their lineup in 2019. Ketel Marte may be just the fella.
Marte wasn't considered much of a prospect when he broke in with the Seattle Mariners back in 2015, and he's had at least as many downs as ups in four seasons since then. He's still only 25, however, and he was last seen with serious helium.
After a slow start to 2018, Marte rebounded with a .277/.353/.483 slash line and 13 home runs from May 9 through the end of the year. On the whole, 2018 was a season in which he made progress with his strike zone discipline, contact rate and power output.
Marte's bat alone could become an All-Star-caliber quality if he keeps that up in 2019. Moreover, there's a decent chance that a move to center field will provide greater exposure for his athleticism.
Atlanta Braves: A.J. Minter, LHP
A breakout star on the Atlanta Braves? Man, pick one. They're as rich in young cornerstones and up-and-coming prospects as any team in MLB.
But even if we may regret it later, we're going to put the spotlight on A.J. Minter.
For now, the 25-year-old reliever may be most famous for looking uncannily like a left-handed Craig Kimbrel. Another commonality he shares with Kimbrel is a mid-to-high 90s fastball as the basis for his arsenal.
However, Minter also packs a filthy cutter, and he was mixing in a changeup by the end of 2018. Factor in steadily improving control, and even the 3.23 ERA and rate of 10.1 strikeouts per nine innings he put up don't do his potential justice.
Minter's talent is begging for the kind of exposure that's typically reserved for closers. Lucky for him, Atlanta's ninth-inning situation is begging for a solid solution for 2019.
Baltimore Orioles: Tanner Scott, LHP
The 2019 Baltimore Orioles could be even worse than the iteration that racked up 115 losses in 2018. When it comes to exciting talent, there's not a lot of it.
As wild cards go, however, Tanner Scott isn't so bad.
If nothing else, the 24-year-old lefty has an explosive fastball. His heater averaged 97.1 mph in 2018. Among qualified southpaw relievers, only Aroldis Chapman, Felipe Vazquez and Jose Alvarado did better.
Throughout both his minor league (6.6 walks per nine innings) and major league (4.9 BB/9) careers, Scott's problem has been controlling the ball. But as he shifted his position on the rubber throughout 2018, some stability did materialize toward the end of the year. His reward was a strong finish after August 18.
Any more of that, and Scott may emerge as a closer candidate in 2019. That'll do for a silver lining in Baltimore.
Boston Red Sox: Rafael Devers, 3B
The hype was real when the Boston Red Sox called Rafael Devers up in July 2017. The early returns (.819 OPS and 10 homers) were highly encouraging, but Devers disappointed as a sophomore in 2018.
Good thing he's still only 22, not to mention supremely talented.
Devers has impressive all-fields power for such a young player. Whether he can tap into that consistently hinges on him toning down an approach that's been overly aggressive. To this end, it's encouraging that his swing rate took a nosedive at the end of 2018. That and a healthy shoulder coincided with a strong late-season surge, followed by some heroic moments in Boston's World Series run.
In light of his poor defensive metrics, the Red Sox need Devers' bat to carry him at third base. That'll happen if he keeps his OPS above .800 while providing 25-plus homers per year, which he can start as soon as 2019.
Chicago Cubs: Ian Happ, OF
Ian Happ was in the same boat as Devers going into 2018. He initially lived up to the hype after the Chicago Cubs called him up in May 2017, but he struggled to get on track in his first full season.
Happ, 24, also finished worse than he started. He had his OPS over .840 as late as July 24. From then on, he slumped with a .607 OPS and a 37.7 strikeout rate. He was simply swinging through too many fastballs.
Still, Happ did tighten up his zone discipline and make more frequent hard contact in 2018. If he can stop swinging through so many fastballs, carrying those trends over into 2019 should help get him closer to his rookie performance: an .842 OPS and 24 homers in 115 games.
Or so the Cubs hope, anyway, because Happ is only one guy they need more out of this year.
Chicago White Sox: Eloy Jimenez, OF
They'll be greeting a 22-year-old who's dominated at every level he's played at since 2016. Some highlights include a .961 OPS and 22 homers across Double-A and Triple-A in 2018 and literal light-tower power in the Carolina League's 2017 home run derby.
What separates Jimenez from other slugging prospects is his acumen for hitting. Though he hasn't posted ridiculous walk rates, he's typically avoided high strikeout rates. He's less Joey Gallo and more Nelson Cruz.
Jimenez's bat will need to work, because he's not going to get far on his glove. Luckily for the White Sox, his bat may contain one of the best slugging seasons ever by a rookie.
Cincinnati Reds: Luis Castillo, SP
Nick Senzel is the Cincinnati Reds' answer to Jimenez. He's coming off a broken finger, however, and there isn't a clear avenue to playing time for him on the Reds' veteran-laden roster.
Therefore, we side with Luis Castillo as Cincinnati's more immediate breakout candidate.
Granted, we thought the same thing heading into 2018, only to watch Castillo largely struggle through his first full season. He did finish strong, though, posting a 2.63 ERA in 14 starts after July 1.
According to Castillo himself, per MLB.com's Mark Sheldon, the difference was in learning to trust his stuff. That was most evident in the increased use of his excellent changeup in August and September. Of course, the 26-year-old's fastball also picked up some serious steam toward the end.
Any more of that, and Castillo could find himself pitching in his first All-Star Game in July.
Cleveland Indians: Shane Bieber, SP
In light of the talented players they've lost this winter, the Cleveland Indians are going to need something extra from their incumbents in 2019. To that end, Shane Bieber is a fascinating case.
Cleveland drafted Bieber in the fourth round of the 2016 draft, but his excellent command allowed him to rise quickly for his major league debut last May. Then a wall seemed to hit him, as he put up a pedestrian 4.55 ERA in 114.2 innings.
Yet, the 23-year-old struck out (118) five times as many batters as he walked (23), and he only allowed 13 homers. Such numbers raise the suspicion of bad luck. Statcast's xwOBA metric—based on quality of contact—would seem to confirm that was the case.
Besides which, what's not to like about a command artist with a 93.1 mph fastball and a slider, curveball and changeup in his back pocket? Nothing. That's what.
Colorado Rockies: David Dahl, OF
The Colorado Rockies offense didn't have much outside of Nolan Arenado, Trevor Story and Charlie Blackmon in 2018. It showed when they went on the road, where they had a .665 OPS.
Daniel Murphy should help fix that in 2019, but perhaps not as much as David Dahl.
Dahl was a top-10 draft pick all the way back in 2012. He was a generally well-regarded prospect in ensuing years, but the injury bug just wouldn't leave him alone. Even after he broke in with the Rockies in 2016, a stress reaction in his rib sidelined him for all of 2017.
But as a general rule, Dahl hits when he's healthy. So it went late in 2018 after he'd recovered from a broken foot, as he finished with an .897 OPS over 45 games. At work there is an all-fields, line-drive-oriented stroke that's perfect for exploiting Coors Field's wide gaps, and which could make Dahl an All-Star.
Detroit Tigers: Christin Stewart, DH
Christin Stewart might prove to be the first major fruit harvested from the Detroit Tigers farm during their rebuild.
The 25-year-old has never appeared in any season-opening top 100s, mainly because he's always been limited in what he can do. He can't field. He can't run. He can only hit.
Fortunately for the Tigers, that's something he does well. Stewart racked up 83 homers in the minors between 2016 and 2018. No less important is how he narrowed the gap between his walk (13.9 BB%) and strikeout (20.7 K%) rates in 122 games with Triple-A Toledo in 2018.
Though Stewart's power can't be described as "booming," there's enough there for a 25-homer season right out of the gate in 2019. That plus a consistent approach could make him the best hitter in a Detroit lineup that can no longer revolve around Miguel Cabrera.
Houston Astros: Josh James, SP
He may be MLB.com's No. 5 prospect, but 21-year-old outfielder Kyle Tucker met his match when the Houston Astros promoted him to The Show in 2018. Further development is in order for him.
This should mean more eyes on Josh James.
There wasn't much to say about the 25-year-old righty as recently as 2017, but then came a 3.23 ERA and a 13.5 K/9 in 23 outings at Double-A and Triple-A in 2018. He then arrived in the majors and flashed a fastball that averaged 97.1 mph and got as high as 101 mph. His slider and changeup impressed, too.
The catch is that James' command is somewhere below Bieber's in quality. But with stuff like his, he can survive as a regular in Houston's rotation despite that. Should a late addition force him to the bullpen, he could be even more dominant pitching in short stints.
Kansas City Royals: Adalberto Mondesi, SS
As of now, Adalberto Mondesi might be most famous for being Raul Mondesi's son or for being the first player ever to make his major league debut in the World Series.
This should change in 2019.
Though Mondesi is a couple years removed from being a top prospect, he's only 23 and coming into his own in a hurry. He started pushing Alcides Escobar for playing time at shortstop with the Kansas City Royals last June. When the year ended, he had put up an .804 OPS with 14 homers and 32 stolen bases in 75 games.
Though Mondesi is a free-swinging type, his hard contact rate exploded in 2018 anyway. More of that will keep his slugging percentage high and his on-base percentage high enough to keep the steals coming. Otherwise, he can also play a good shortstop.
Though the AL is already teeming with All-Star-caliber shortstops, it had better make room for one more.
Los Angeles Angels: Ty Buttrey, RHP
The Los Angeles Angels have three 20-something starting pitchers—Andrew Heaney, Tyler Skaggs and Jaime Barria—who could take top billing here. But from afar, they appear no better than "fine."
The spotlight is thus on Ty Buttrey, who the Angels picked up in the trade that sent Ian Kinsler to Boston in August. He was pitching for them not long after, and he pitched well with a 3.31 ERA and 20 strikeouts in 16.1 innings.
The 25-year-old righty works off a fastball that sits at 96 mph and climbs as high as 100 mph, and mixes in a slider and changeup. Albeit in a very small sample, his weapons had elite bat-missing ability even within the strike zone.
That's about as telling a mark for a dominant closer as anyone could ask for. If Buttrey keeps it up, he'll ensure the Angels won the Kinsler trade.
Los Angeles Dodgers: Alex Verdugo, OF
With Yasiel Puig and Matt Kemp out of the picture, there's room in the Los Angeles Dodgers outfield for an unusual suspect to own the stage.
That means you, Alex Verdugo.
The 22-year-old has been a strong presence in top prospect lists over the last two years, and it's easy to see why. He's put up a .321/.389/.452 line in 208 games for Triple-A Oklahoma City, with barely more strikeouts (97) than walks (86). These are the marks of a natural-born hitter.
If there's a concern with Verdugo, it's what Baseball America calls an "indifferent attitude" that's plagued him on defense and on the basepaths. If he doesn't get that squared away, he may not be long for the Dodgers.
For now, however, he appears locked into regular action in right field. With little left to prove in the minors, he should know not to sabotage his best chance yet at major league stardom.
Miami Marlins: Tayron Guerrero, RHP
The Miami Marlins are probably putting all their hopes in young center fielder Lewis Brinson to be their big breakout star in 2019. Trouble is, his hitting approach needs a lot of work.
Tayron Guerrero is no work of art in his own right, but he at least has one vital ingredient for becoming a shutdown reliever: heat.
The 28-year-old righty averaged 98.8 mph with his fastball in 2018 and even got it up to 104 mph on one occasion. Only he, Chapman and Jordan Hicks explored the territory above 102 mph more than once.
Guerrero nonetheless finished with a modest 5.43 ERA and 10.6 K/9 in 2018. He particularly struggled when he for some reason drastically reduced his fastball usage.
That could either be a warning or a blip. We'll put our chips on the latter and trust that Guerrero's fastball will ultimately pave the way to Miami's closer role.
Milwaukee Brewers: Brandon Woodruff, SP
Of the young right-handed trio of Brandon Woodruff, Corbin Burnes and Freddy Peralta, only Woodruff seems ticketed for the Milwaukee Brewers' Opening Day rotation.
That's either because he's the only one who's gone yard off Clayton Kershaw in the playoffs, or because he's the closest to realizing his potential as a star.
Though the 25-year-old pitched mostly in relief for the Brewers in 2018, he was no ordinary reliever. He regularly pitched multiple innings, culminating in a strong 5.1-inning effort in Game 5 of the National League Championship Series.
All the while, Woodruff flashed a mid-90s fastball with a sharp slider and changeup. Even if he needs to dial it back in a full-time starting role, his command is such that he shouldn't need to overpower hitters all the time.
Failing that, he can always fall back on a role as a dominant multi-inning reliever.
Minnesota Twins: Willians Astudillo, C/UTIL
Perhaps this is wishful thinking on behalf of every baseball fan's favorite large adult son. Or, perhaps the Minnesota Twins really do have something in Willians Astudillo.
Astudillo's major league debut in May 2018 came at the end of a nine-year journey through the minor leagues. All the while, he was a curiosity for how he almost always put the ball in play. In 2,461 total plate appearances, he drew only 85 walks (3.5 BB%) and struck out 81 times (3.3 K%).
So it went for Astudillo in the majors, as he collected only two walks and three strikeouts in 29 games for the Twins. He also hit .355 with an .887 OPS, thereby teasing that his unique approach might actually work at the highest level.
Did we mention that Astudillo is also a primary catcher who can fill in at every other position on the diamond? Because that's a thing with him, too. He's an unpredictable defender, to boot, and he runs well for a self-professed "chubby" guy.
The 27-year-old was last seen pimping the ever-loving heck out of a home run in the Venezuelan Winter League. That might not be an omen...but, nah, it's probably an omen.
New York Mets: Zack Wheeler, SP
This is kinda-sorta-cheating. After all, Zack Wheeler is coming off a 2018 season in which he notched a career-best 3.31 ERA over 182.1 innings. It's hard to break out any more than that.
Trust us. He can do it.
As great as Wheeler was in 2018, the really good stuff didn't come until the second half, when he finished with a 1.68 ERA and permitted just a .489 OPS in 11 starts.
His fastball velocity was peaking around then, and his slider, curveball and splitter were practically equal partners among his secondary offerings. More subtly, he took a cue from Jacob deGrom and got a lot better at disguising the release points and flight paths of his pitches. The effect could be devastating.
Never mind just All-Star potential. If Wheeler picks up where he left off, he might even make a run at the NL Cy Young Award.
New York Yankees: Luke Voit, 1B
The New York Yankees don't have many players who aren't already established stars, so we're going to go in a slightly different direction and posit that Luke Voit is for real.
The Yankees picked Voit up from the St. Louis Cardinals last July for Chasen Shreve and Giovanny Gallegos. He seemed to be little more than a depth piece, but then came an astonishing 39-game stretch in which he slashed .333/.409/.689 with 14 long balls.
That was a surprising amount of power for a guy who'd hit only 65 homers in six minor league seasons. Voit, 27, credited it to natural evolution of both his approach and his swing. He did indeed show good zone discipline, and he generated more fly balls with power to all fields.
It's a bit much to expect Voit to carry on as one of MLB's best hitters, but he should stand out in a relatively weak crop of American League first basemen.
Oakland Athletics: Jesus Luzardo, SP
Presently, the Oakland A's rotation is Mike Fiers and a bunch of question marks. They do have an ace in the hole, though, and his name is Jesus Luzardo.
"I think Jesus is going to come into spring training and be a factor," A's general manager David Forst said last October, per Ben Ross of NBC Sports Bay Area. "I don't think we have to hide that."
Beyond being Oakland's best prospect, Luzardo is the best left-handed pitching prospect in baseball. Though he's only 21, he displays advanced command of a mid-90s fastball, a fading changeup and an above-average curveball.
Luzardo advanced from High-A to Triple-A in 2018, his first full professional season. He finished with a 2.88 ERA and four times as many strikeouts (129) as walks (30) in 109.1 innings. Once he joins the A's in 2019, he can get to work on an AL Rookie of the Year campaign.
Philadelphia Phillies: Jorge Alfaro, C
There's been some talk this winter about whether the Philadelphia Phillies should be looking for a catcher, but general manager Matt Klentak is content with Jorge Alfaro.
"I think what Jorge showed last year was incredible growth for a first-year catcher, both on the offensive side and the defensive side," Klentak told Scott Lauber of the Philadelphia Inquirer in December.
The 25-year-old did have some growing pains in his first full major league season 2018. He put up a modest .731 OPS with 10 homers, and he led the NL with 10 passed balls.
Even despite those passed balls, however, Baseball Prospectus' metrics rated Alfaro as a top-five defensive catcher. He also cut way back on his strikeouts as the season wore on, which contributed to a strong .788 second-half OPS.
If Alfaro carries on in this fashion in 2019, he can throw his name into the best catcher in baseball discussion.
Pittsburgh Pirates: Jameson Taillon, SP
Jameson Taillon is the Pittsburgh Pirates' answer to Wheeler. He was darn good in 2018, but he can do even better in 2019.
Though the 27-year-old put up a 3.20 ERA over 191 innings last season, he didn't really take off until May 27. That's when he kicked off a 22-start stretch highlighted by a 2.71 ERA with 131 strikeouts and 30 walks in 139.2 innings.
That fateful date is when Taillon made a slider a featured part of his arsenal, alongside a 95.2 mph fastball and a sharp curveball. Though he seemed to pull that slider out of thin air, you'd never know it from looking at it.
Taillon's next trick might be to break out a reliable changeup, a pitch that has thus far proven difficult for him to master. Even if he fails to do so, however, he's a potential All-Star and Cy Young Award contender.
San Diego Padres: Fernando Tatis Jr., SS
The San Diego Padres are teeming with 20-somethings with star potential, but the best has yet to arrive. That'll happen when the Padres call up Fernando Tatis Jr. to play shortstop.
Tatis was a 17-year-old with a recognizable name—his old man spent 11 years in the majors—when the Padres acquired him from the White Sox for James Shields in 2016. He's since blossomed into MLB.com's No. 2 prospect with back-to-back excellent seasons in the minors.
Though there's plenty of swing-and-miss in Tatis' offensive game, he makes up for it with a feel for the barrel that's produced a .280 career batting average and 38 homers since 2017. He's also a highlight machine on defense.
Tatis, now 20, has only advanced as far as Double-A San Antonio, but his major league debut isn't far off. The sooner he arrives, the sooner he can make a run at the NL Rookie of the Year.
San Francisco Giants: Dereck Rodriguez, SP
Steven Duggar and Chris Shaw will get their shot to settle as regulars in the San Francisco Giants outfield, but neither will become a star until he stops swinging and missing so much.
We thus find ourselves looking at another son of a famous father: Dereck Rodriguez.
Ivan Rodriguez's 26-year-old son was originally drafted as an outfielder by the Minnesota Twins in 2011. He converted to a pitcher in 2014, and he finally made his major league debut last May. What followed was a 2.81 ERA over 118.1 innings.
Rodriguez's trick was to use a diverse repertoire of pitches to stifle dangerous contact. He ranked seventh in xwOBA on batted balls, in between Miles Mikolas and Carlos Martinez. His next challenge is improving his strikeout rate, which finished at a modest 6.8 per nine innings in 2018.
That ought to be doable with his stuff, and he'll be deserving of All-Star attention if he gets it done.
Seattle Mariners: Yusei Kikuchi, SP
It's debatable whether a guy who's already been a star in Japan really has any more breaking out to do.
But since this is an excuse to sing Yusei Kikuchi's praises, well, why not take it?
The Seibu Lions posted the 27-year-old lefty in December, and he signed with the Seattle Mariners about a month later. He wouldn't seem to have the same upside as fellow imports Yu Darvish or Masahiro Tanaka, but his stuff should play in the majors.
The most hopeful sign is what Kikuchi did in 2017. He put up a 1.97 ERA with 217 strikeouts and 49 walks in 187.2 innings. His stuff—namely a low-to-mid 90s heater and a sharp slider—was popping that year.
No thanks to some trouble with his left shoulder, Kikuchi slipped a bit in 2018. Provided his shoulder is back in shipshape for 2019, a run at the AL Rookie of the Year is in the cards.
St. Louis Cardinals: Jack Flaherty, SP
Only five rookie pitchers have ever logged over 150 innings and struck out at least 10 batters per nine innings: Kerry Wood, Dwight Gooden, Hideo Nomo, Darvish and the guy pictured above.
The Cardinals drafted Jack Flaherty at the end of the first round in 2014. He spent his first couple professional seasons in Alex Reyes' shadow, but he was was finally a consensus top-100 prospect going into 2018. He ultimately helped stabilize St. Louis' rotation with a 3.34 ERA in 28 starts.
Flaherty worked off a fastball that sat at 92.7 mph and got as high as 97.3 mph, with a sharp slider as his primary finishing pitch. As his arm slot went higher, he settled into a low contact rate and finished with an 11.3 K/9 in the second half.
Flaherty's final remaining project is ironing out his control. Even if that takes more time, he might make the All-Star Game on whiffs alone.
Tampa Bay Rays: Willy Adames, SS
If anyone's in the mood for a good trivia item, Jason Bartlett is the only Tampa Bay Ray to ever make the All-Star Game as a shortstop.
He should soon have company in the person of Willy Adames.
Adames was one of MLB's better prospects when the Rays promoted him last May, and he sent good vibes through the roof at Tropicana Field when he homered off Chris Sale for his first major league hit. But by the end of July, he was struggling to the tune of a .552 OPS.
A bat like that will play at short, perhaps to a point where Adames will overshadow some of the greats at the position in the American League.
Texas Rangers: Nomar Mazara, OF
The Texas Rangers have a secret weapon in their bullpen in flamethrowing righty Jose Leclerc. But after finishing as arguably a top-five reliever in 2018, all he's really missing is recognition.
So, here goes with yet another insistence that Nomar Mazara is about to break out.
Mazara was universally considered an elite prospect when he joined the Rangers in April 2016, and he's had his moments. Altogether, however, it's hard to be impressed by the .746 OPS or 60 homers he's compiled over 421 games.
Still, Mazara is only 23. He's also coming off the best xwOBA of his career, which is mainly owed to his career-best 90.5 mph average exit velocity. And while he doesn't have them all figured out just yet, he's been making progress with his split against left-handed pitchers.
Since he's as close to breaking out as he's ever been, maybe 2019 will finally be the year that Mazara clicks.
Toronto Blue Jays: Vladimir Guerrero Jr., 3B
Wrapping up our series on famous offspring is the best of them all: Vladimir Guerrero Jr.
Vlad's dad, Vlad, was elected into the Baseball Hall of Fame last year. The Guerrero family will have another cause to celebrate when Vlad Jr. gets called up to the Toronto Blue Jays, which should be when they're done artificially suppressing his service time in mid-April.
All Guerrero will have to do then is his usual thing of clobbering the daylights out of the ball.
Even his .331/.414/.529 career slash line in three minor league seasons doesn't do him justice. He just slashed .381/.437/.636 in a 2018 season that took him from High-A to Triple-A. He hit 20 bombs, with only one more strikeout (38) than walks (37).
These are ridiculous numbers for anyone. They ought to be impossible for a guy who won't turn 20 until March 16. Yet there they are, and they're absolutely a prelude to special things to come in the majors.
Washington Nationals: Victor Robles, OF
The Phillies are now the "clear-cut favorite" to sign Bryce Harper, according to Bob Nightengale of USA Today. If that happens, Harper's time in Washington will be over.
Good thing the Washington Nationals have Victor Robles standing by. He's a legit five-tool talent who ranks behind only Guerrero, Tatis and Jimenez on MLB.com's top 100 prospect list.
There are really only two nits to pick with Robles. He's had some injuries, including a hyperextended elbow that limited him to 52 minor league games in 2018. He also hit only two homers in the minors last year, which reflects how his power lags behind his other tools.
Robles is still only 21, however, so his body shouldn't be broken beyond repair. He's also fresh off a tantalizing 21-game tease with the Nats at the end of 2018, which included an .874 OPS and three homers.
If he gets the job, Robles can do in 2019 what Harper did in 2012: win the NL Rookie of the Year.