Tracking the Performance of the Boston Red Sox's Prospects in the AFL

The Boston Red Sox have a long history of supplying the Arizona Fall League with some interesting players. From Nomar Garciaparra to Dustin Pedroia to more recent additions like Mookie Betts and Christian Vazquez, the Surprise Saguaros have hosted many prominent Red Sox throughout the years.

That’s the case once again in 2014, as Rusney Castillo and a host of additional Red Sox prospects have flocked to Arizona to test their skills against varying levels of competition. The AFL features top prospects, recovering young MLBers and minor league journeymen on the brink of the majors, all playing against one another on one of six AFL teams.

Now, with 18 AFL games in the books, we can track the performance of the Red Sox who are playing in Arizona this year.

Keep in mind that the sample sizes are very small and the level of competition varies, so these stats truly hold next to no predictive value. That being said, we can still look for clues in certain scenarios in order to see if any of the Sox’s prospects have made progress with areas of personal development.

We’ll just keep this list to players who can reasonably be considered prospects, so with all due respect to Robby Scott and Madison Younginer, we won’t be tracking their progress here.

Rusney Castillo, CF

Keith Srakocic/Associated Press

AFL Stats
36 AB, .278/.333/.361, 10 H, 3 BB, 6 K, 3 2B, 0 HR, 1 SB

It’s getting harder and harder not to be really excited by what Castillo may bring to the table for the Red Sox in 2015.

While we’re dealing with small sample sizes all the way around here, Castillo hit .333/.400/.528 in 40 plate appearances with the Red Sox near the end of the 2014 season, showcasing his power/speed combo and playing impressive defense in center field. He’s followed up that run with a nice start to his AFL career, notching 10 hits in his first 36 at-bats and stealing a base to boot.

Castillo has been sitting out for the better part of a week now because of a sore hand/thumb, according to WEEI.com’s Alex Speier, so his progress has been momentarily slowed. And as Brian MacPherson of the Providence Journal noted on Monday, Castillo may not play again until Roberto Clemente League in Puerto Rico starts up later this winter.

But when Castillo has been on the field, he’s been impressive, and the Red Sox have to like what they’ve seen from their investment to this point.

Keith Couch, RHP

Kelly O'Connor, www.sittingstill.net

AFL Stats
4 GS, 17 IP, 5.82 ERA, 6 K, 2 BB, 1.71 WHIP, 1 HR

It’s been a disappointing stint in Arizona so far for Couch, who’s coming off a really nice year with Portland in Double-A. During the 2014 season, Couch held hitters to a 2.96 ERA in 100.1 innings, giving up just three homers and surrendering just 22 walks during that span.

But while it may be true that AFL stats don’t hold a ton of predictive value, giving up 27 hits in 17 innings isn’t a great sign for Couch. The 24-year-old has been hit hard and often in his four AFL starts to this point, missing few bats and allowing far too much contact.

Yet Couch has never been viewed as a particularly interesting prospect, and this AFL stint won’t do much to help his case. Especially in a system as loaded with starting pitching prospects as Boston, it’s tough to see him making much of an impact at the MLB level.

Couch very well may spend the majority of 2015 as a starter in the minors, but if he’s going to stick in the majors, it will likely be as a reliever. For now, he’ll attempt to right the ship in Arizona before looking to reach Triple-A at some point in 2015.

Sean Coyle, INF

Christian Petersen/Getty Images

AFL Stats
36 AB, .167/.302/.278, 6 H, 6 BB, 16 K, 2 2B, 0 HR, 3 SB

There’s no way around it: Coyle’s had a pretty rough start to his AFL career through 10 games. The 22-year-old infielder has struck out 16 times in just 36 at-bats, has only reached base 12 times and is sporting an ugly .167 average. His numbers have been disappointing for a player who figures to have a shot to start 2015 in Triple-A.

Of course, Coyle’s struggles now don’t wipe out his impressive 2014 campaign. Coyle hit .295/.371/.512 in 384 PA in Portland in 2014, making the U.S. Futures Game roster and gaining some relevancy on a national level. It wouldn’t be shocking to see him sneak onto the back of a top-150 prospects list this offseason for the publications that dive that deep.

But Coyle will need to demonstrate that his hit tool can play up against superior competition, and any defensive versatility he can add to his resume will greatly aid him in his quest to reach the majors, too. He’s obviously blocked at second base in the Boston organization, and he truly doesn’t have the arm to play third.

Aaron Kurcz, RHP

Kelly O'Connor, www.sittingstill.net

AFL Stats
6 G, 7 IP, 5.14 ERA, 8 K, 6 BB,  1.71 WHIP, 1 HR 

Kurcz is still somewhat recently removed from Tommy John surgery, so his command troubles can be forgiven to a certain extent. But it’s still not a great sign that Kurcz has walked six batters in seven innings in the AFL after walking 22 batters in 42 innings during the regular season.

An undersized right-hander who can reach the mid-90s with his fastball, per SoxProspects.com, Kurcz is mildly interesting as a middle reliever prospect who could be on the precipice of a call-up to the majors with a decent 2015 campaign. He’ll need to prove his stuff works against more advanced hitters, though, and that his lack of size won’t prevent him from reaching his ceiling.

There aren’t a whole lot of stats with less meaning than AFL reliever ERA, and it’s a good sign that Kurcz is still missing bats with eight strikeouts in just seven innings. Demonstrating the ability to throw strikes consistently will make all the difference in the world for Kurcz, and that’s what we should keep our eyes on this season.

Deven Marrero, SS

Christian Petersen/Getty Images

AFL Stats
31 AB, .323/.475/.452, 10 H, 9 BB, 9 K, 4 2B, 0 HR, 2 SB

Good luck trying to figure out Marrero’s offensive profile. The 24-year-old hit .291/.371/.433 in Portland in 2014 and looked to be on the verge of becoming one of the minor league’s more interesting shortstop prospects. Then Marrero hit just .210/.260/.285 at Triple-A Pawtucket, lending credence to the opinion that he’s never going to be much of an offensive threat.

Yet here we are a few months later and Marrero is tearing up the AFL, notching 10 hits and nine walks in his first 31 at-bats and swiping two bases with doubles power to boot. Marrero’s defense is MLB-ready right now, so any positive steps with his bat are great to see.

Regardless of how Marrero performs the rest of the way in Arizona, expect him to start 2015 back in Triple-A where he’ll attempt to show he can be more than an automatic out at the plate. If his offense moves forward, he could be a second-division starter at shortstop. If not, he should enjoy a long career as a classic MLB utility infielder.