Boston Red Sox: Top Candidates to Enjoy Breakout Seasons in 2015

With the 2015 Major League Baseball season underway, the Boston Red Sox are looking to rebound from an unexpected last-place finish in 2014.  New additions Hanley Ramirez and Pablo Sandoval join an All-Star-laden lineup that returns David Ortiz, Dustin Pedroia, Mike Napoli and Shane Victorino.

Rick Porcello, Clay Buchholz and veteran closer Koji Uehara headline a pitching staff that Red Sox fans hope will be good enough to ride Boston's potent offense to the postseason.  If the Sox are to return to the playoffs, they'll likely also need significant contributions from a few players who haven't yet made their mark in MLB.

Here are the Red Sox's top candidates to break out in 2015.

Mookie Betts

If the Mookie Betts bandwagon wasn't full already, it undoubtedly is now after Betts' Opening Day home run in Philadelphia.  From Michael Silverman of the Boston Herald:

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The Red Sox’ fastest-rising star, their most dynamic young player, rose to the occasion once again in yesterday’s 8-0 rout of the Phillies.

Betts hit a home run off Cole Hamels, one of the best pitchers in the game, in his second at-bat of the season, and also singled and scored another run following a walk.

The stage does not seem to matter for the 22-year-old leadoff hitter and center fielder who was a Double-A second baseman a year ago.

"

To this point in his brief professional career, Betts has had great success at every stop along the way.  As a 20-year-old in 2013, Betts hit .314 with 15 homers, 65 RBI, 38 steals and a .417 on-base percentage through 462 at-bats at two levels of Single-A.

He began last year in Double-A but was promoted after just 54 games with a .355 average and a .443 OBP.  Over his first 23 contests with Triple-A Pawtucket, Betts batted .322 with a .425 OBP.  In late June, the 21-year-old got the call-up to Boston despite less than half a season combined in Double-A and Triple-A.

Betts promptly hit .291 and posted a .368 OBP in 52 major league games last year.

His torrid pace continued this spring in Florida.  Should such an honor exist, Betts was arguably the Grapefruit League's MVP.  In 19 exhibition contests, he scored 15 runs and had 42 total bases while batting .429 with a .467 OBP and a .750 slugging percentage.

It's been a meteoric rise for Betts over the past year, but everything he's done so far suggests he'll be a big-time player for the Red Sox this season.

Xander Bogaerts

The Red Sox's former No. 1 prospect burst onto the scene in the fall of 2013.  Xander Bogaerts entered the postseason with just 18 career major league games under his belt, but he hit .296 with a .412 OBP in 27 playoff at-bats to help Boston take home the World Series crown.

In the wake of sky-high expectations, Bogaerts struggled the following season.  The shortstop finished his rookie year with a .240 average and a .297 OBP over 144 games.

With many new faces on board and a hot new prospect in Betts, the attention has shifted away from Bogaerts in 2015.  In March, Bogaerts told ESPNBoston.com's Gordon Edes:

"

I like it better this way. I've always been a laid-back guy. For me, this is much better. … 

Now there's Mookie, and they've signed a lot of good players. To have [the spotlight] on them is good for me. …

I learned a lot last year. That was basically my first full year and the most important thing I learned I needed was to be stronger. I was pretty worn down halfway through the season. I'm better prepared.

"

The stats back up Bogaerts' claim.  Through April and May of 2014, he hit .304 with a .397 OBP, but over the final four months of the year, those numbers dropped to .203 and .236.  If he can return to his early-season form, Bogaerts is capable of living up to his potential in 2015.

Rusney Castillo

Currently in Pawtucket, nobody expects Rusney Castillo to last long in the minor leagues—especially considering his base salary of $10.5 million this year.

In 10 major league games last season, the Cuban import hit .333 with two home runs, six RBI and a .400 OBP.  Castillo's recent spring training numbers are virtually identical.  An oblique strain held him out of all but nine contests, in which he batted .310 with two homers, five RBI and a .621 slugging percentage.

There's a small sample of work to go on with Castillo, but unlike Betts and Bogaerts, he's not an up-and-coming youngster.  Castillo is 27 years old and likely already in his prime.  There's no reason to think he won't be able to step right in and be a quality big league player.

Depending on when Castillo is brought up and how many plate appearances he's able to accumulate, there could be an American League Rookie of the Year award in his future.

Anthony Varvaro

Anthony Varvaro has already proven himself to be a quality major league pitcher, but as a former middle reliever in the National League, he's a name Boston fans probably aren't too familiar with.  With the Atlanta Braves, in 2013 and 2014 Varvaro posted a combined 2.74 ERA and 1.19 WHIP in 128 innings spanning 123 appearances.

The Red Sox acquired Varvaro from Atlanta back in December for minor league pitcher Aaron Kurcz and cash.  Via Mass Live's Jen McCaffrey, Boston Manager John Farrell said the following last month about Varvaro:

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We were somewhat surprised a guy of his performance was available. He's been very good against left-handed hitters and getting an understanding to his role a year ago, he was almost used as a left-handed reliever because of his success against left-handed hitters. He's got good stuff, he's performed above average the last two years at the major-league level. He became quickly attractive to us.

"

Tim Britton of the Providence Journal writes:

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Varvaro possesses one of the starkest reverse splits in all of baseball. The right-hander has held lefties under a .200 batting average in his career, including a .149 mark last season — fourth-best among right-handed relievers in baseball last season. In fact, Varvaro was tougher on lefties last season than Andrew Miller.

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Miller made a name for himself with his performance out of the bullpen for Boston in 2014, then turned it into a four-year, $36 million payday from the New York Yankees in the offseason.  Varvaro could be in line for a similar breakout campaign with the Red Sox in 2015.

Mark Vandeusen is a Featured Columnist covering the Boston Red Sox for Bleacher Report. Follow him on Twitter @LucidSportsFan. Unless otherwise noted, all statistics via RedSox.com and contract information via Spotrac.com.