Stock Up, Stock Down on MLB's Top 10 Pitching Prospects After Week 6

Baseball fans are currently in the midst of a golden age in terms of young starting pitching. Never before have pitchers thrown harder or been nastier than they are today. 

Judging by the abundance of talent in the minor leagues, that pitching dominance doesn't figure to end anytime soon. Arms like Julio Urias, Tyler Glasnow and Lucas Giolito headline the next wave of stud hurlers. 

Over the next few slides, we'll take a look at some of the game's top young pitching talents. Analyzing their performances over the course of 2015, we'll decide if we're buying or selling stock in baseball's top 10 pitching prospects.

To do so, we'll use MLB.com's prospect rankings. Any pitcher who is currently in the major leagues, like Noah Snydergaard and Carlos Rodon, will be skipped.

Let's start with Miami's top overall prospect.

Tyler Kolek, Miami Marlins

2015 Stats

3-2, 31.1 IP, 4.60 ERA, 4.07 FIP, 6.89 K/9, 4.31 BB/9

The Skinny

The Miami Marlins selected Tyler Kolek with the second pick of the 2014 draft, but the right-hander has struggled to live up to that hype in his young career.

After recording a 4.50 ERA in 22 innings of rookie ball, Kolek has posted a similar ERA in just over 31 innings at Single-A. A big reason for that inflated ERA is his command, as the 19-year-old has a walk percentage of over 10 percent for the second straight season.

The Verdict: Stock Down

Marlins fans shouldn't be overly concerned about their prized youngster. At just 19, Kolek has plenty of time to develop into a front-line starter. 

But his inability to consistently throw strikes so far in his brief career should raise some eyebrows, especially since the big strikeout numbers have yet to appear.

Andrew Heaney, Los Angeles Angels

2015 Stats

5-0, 43.1 IP, 3.12 ERA, 8.9 K/9, 2.9 BB/9

The Skinny

Andrew Heaney failed to make the Los Angeles Angels rotation out of camp, but the southpaw is doing everything in his power to force a promotion from Triple-A.

Heaney is undefeated with a 3.12 ERA in eight starts this season. After a mediocre cup of coffee with the Miami Marlins last season, it's nice to see Heaney's strikeout totals return. Meanwhile, the 23-year-old has continued to throw strikes on a consistent basis. 

It doesn't seem like a matter of if Heaney will be promoted this season, but when. Andrew Petrucci of FanSided suggested using Heaney in a bullpen role earlier this month:

"

Andrew Heaney, the Angels top pitching prospect, is most likely to be called up sooner rather than later this season. Projecting as a starter, Heaney is 4-0 in Triple-A, and has already made his MLB debut with the Miami Marlins last season. It may be beneficial to utilize him out of the bullpen depending on how the season shapes up, Heaney could provide the depth the Angels need in the pen and it would help ease him into the league.

"

The Verdict: Stock Up

Between the last two seasons, Heaney has accumulated over 100 innings at Triple-A. He's been consistent at every level, staying around the strike zone and creating ground-ball contact.

Robert Stephenson, Cincinnati Reds

2015 Stats

1-4, 28.2 IP, 5.65 ERA, 5.12 FIP, 9.42 K/9, 6.91 BB/9

The Skinny

Robert Stephenson was Cincinnati's first-round pick back in 2011, but he has only progressed to Double-A so far in his career.

Stephenson has a big arm, with mid- to upper-90s velocity and a solid curve. The development of his changeup or an additional offering will be the determining factor in his potential impact for the Reds. 

As you would expect, Stephenson has had no problems generating swings and misses. His issue has been throwing enough strikes to make those count. Stephenson has walked over 17 percent of the batters he's faced in 2015.

The Verdict: Stock Down

2015 marks the third straight year that Stephenson has has spent time in Double-A. With over 150 innings of data, you would think the flamethrower would be on track for a promotion.

But his lack of command will continue to stunt his ascension through the developmental ranks. Until he proves he can throw consistent strikes, he'll be considered more of a thrower rather than a pitcher.

Luis Severino, New York Yankees

2015 Stats

1-2, 28 IP, 3.86 ERA, 2.85 FIP, 10.93 K/9, 2.57 BB/9

The Skinny

Although Luis Severino is currently on the disabled list with a finger injury, the right-hander has continued his remarkable rise through the New York farm system in 2015.

Severino has suffered through an inflated average on balls in play, but his ERA has managed to remain respectable. With over 10 K's per nine innings and above-average walk rates, there's plenty of reason to believe Severino's ERA will shrink close to the 3.00 mark by season's end. 

The Verdict: Stock Up

At 21, Severino is well ahead of schedule in terms of an MLB debut, which could come as soon as the end of this season. 

Whether it's as a closer or a starter, Severino has the impact stuff to stick around the league for years to come.

Dylan Bundy, Baltimore Orioles

2015 Stats

0-3, 18 IP, 4.50 ERA, 2.16 FIP, 10 K/9, 2.5 BB/9

The Skinny

After missing the entire 2013 season due to Tommy John surgery, Dylan Bundy looked like a shell of himself in six starts at High-A last year.

But the right-hander has eased the fears of Baltimore Orioles fans by flashing his dominant stuff once again in Double-A. Bundy has fanned 26 percent of the batters he's faced, all while walking just five out of 77 opponents. 

The Verdict: Stock Up

Bundy's stock begins and ends with his health. The O's are doing all they can to help their young hurler, as Bundy hasn't pitched more than three innings all season. 

Once Baltimore starts to stretch him out, Bundy won't be too far away from the majors. If he can stay healthy, the sky is the limit for the former No. 4 overall pick.

Henry Owens, Boston Red Sox

2015 Stats

2-2, 37 IP, 3.41 ERA, 4.56 FIP, 7.3 K/9, 6.32 BB/9

The Skinny

The Boston Red Sox need all the starting pitching help they can get, but top prospect Henry Owens isn't ready to answer that call.

Owens has struggled with Triple-A hitters that he dominated at the end of 2014:

• 2014: 38 IP, 10.42 K/9, 2.84 BB/9
• 2015: 37 IP, 7.3 K/9, 6.32 BB/9

It doesn't take a genius to see Owens' issues in 2015. He's never been known for his command, but Owens' noticeable increase in walks is a huge cause for concern.

Conor Duffy at FanSided agrees, noting that Owens' ability to start on a full-time basis has been "called into question" due to his command problems.

The Verdict: Stock Down

The Red Sox may be desperate for pitching help, but Owens isn't in any position to provide that relief right now. 

The bigger concern is Owens' long-term role in the organization. His above-average fastball and outstanding changeup profile as major league pitches, but not if he can't throw them for strikes.

Jon Gray, Colorado Rockies

2015 Stats

1-4, 33.2 IP, 7.75 ERA, 5.13 FIP, 7.49 K/9, 2.94 BB/9

The Skinny

There may not be a more disappointing prospect than Colorado's Jon Gray.

Gray is among the game's best young pitching talents, but he's been shelled at Triple-A after failing to crack the rotation out of spring training. The right-hander has a 7.75 ERA in six starts and has allowed nearly two baserunners per inning.

The 23-year-old is blessed with an electric fastball, but he's finding out that professional hitters can always catch up if they know what's coming. Zach Wilson, Colorado's senior director of player development, echoed that sentiment.

"The stuff is there. It's major league stuff, absolutely," Wilson told Patrick Saunders of the Denver Post. "But it's the consistency that is the next major step for him. Consistency in command, and consistency in seeing him throw a plus-changeup eight out of 10 times, instead of three out of 10 times."

The Verdict: Stock Down

With Colorado headed the wrong way in the standings, Gray's ability to bounce back from a horrendous start may become one of the team's most interesting stories this summer. 

But like many minor league pitchers before him, Gray must become more consistent with his secondary offerings. Until he does, there will be concerns about his ability to headline a major league rotation.

Tyler Glasnow, Pittsburgh Pirates

2015 Stats

2-2, 29.1 IP, 2.76 ERA, 2.87 FIP, 8.9 K/9, 3.07 BB/9

The Skinny

Minus his latest outing, Tyler Glasnow's stock continues to rise with his outstanding performances to begin the 2015 season.

Before giving up five earned runs in 3.2 innings pitched Sunday, the right-hander had allowed just four earned runs in 25.2 innings of work. Glasnow's strikeout rate has remained at it's customary level, while his walk percentage has dipped to just over 8 percent after Sunday. 

Bill Brink of the Pittsburgh Post-Gazette doesn't think Glasnow will remain in Double-A for long.

"

What that means is, he needs another lap through the double-a Eastern League so hitters he's faced before have a chance to adjust, and he can adjust in response. It does no good for a player's development for him to pitch well in his first pass, do great because no one has seen him and then get promoted. Mid-summer at the earliest, maybe August to give him a taste at the end of the season.

"

The Verdict: Stock Up

Glasnow figures to be in Triple-A by the age of 22, accelerating his major league debut with jaw-dropping performances. 

If he continues to throw effective and consistent strikes and avoid hiccups like his Sunday performance, Glasnow could be the next prospect to be used as a bullpen ace if the Pirates are in the playoff hunt.

Julio Urias, Los Angeles Dodgers

2015 Stats

1-2, 36 IP, 3.00 ERA, 2.66 FIP, 11.5 K/9, 2.25 BB/9 

The Skinny

Dominant.

That's the only way to describe Julio Urias in 2015.

The left-hander and No. 2 pitching prospect in baseball has a 3.00 ERA in 36 innings at Double-A. On paper, his run prevention may not be overly impressive, but Urias is competing against players two or three years older than him.

Urias has struck out over 30 percent of the batters he's faced at every level he's pitched at. What makes him truly remarkable is his advanced command of his three different offerings. Urias' pitches are nasty, and he has confidence in each of them, although his changeup does lack behind his fastball and curve at this point in his development.

The Verdict: Stock Up

Urias is coming off his worst outing of the year, but he's as impressive a pitching prospect as there is in baseball. 

He's still years away from his prime, but Urias could wind up being an asset in L.A. sometime this season. 

Lucas Giolito, Washington Nationals

2015 Stats

0-2, 10.1 IP, 5.23 ERA, 1.03 FIP, 13.94 K/9, 2.61 BB/9

The Skinny

The Washington Nationals are being careful with Lucas Giolito. The right-hander only recently made his 2015 debut after participating in extended spring training in an effort to monitor his innings.

Despite a 5.23 ERA in two starts, Giolito has been worth the wait. The 20-year-old has 16 strikeouts in 10.1 innings, including 11 in six innings on May 14. 

As is typical of top pitching prospects, Giolito's velocity is his calling card. He sits in the mid-90s and can approach triple digits when he's amped up. As if that isn't enough, Giolito also throws what Kiley McDaniel of FanGraphs calls a "knockout curveball."

The Verdict: Stock Up

After being roughed up in his first outing of the season, Giolito bounced back in a big way. The electric stuff is still definitely there.

Due to an abundance of pitching talent, Washington has the luxury of being patient with Giolito. He may be further from the majors than any other pitcher on this list, but few others have as much upside. 

Advanced stats courtesy of FanGraphs.