Prospect of the Day: Stolmy Pimentel, RHP, Pittsburgh Pirates

Back in December 2012, the Pittsburgh Pirates traded closer Joel Hanrahan and infielder prospect Brock Holt to the Boston Red Sox, receiving Mark Melancon, Jerry Sands, Ivan De Jesus, and pitching prospect Stolmy Pimentel. This has worked out well for Pittsburgh: Hanrahan got hurt, but Melancon has been outstanding out of the bullpen, and Pimentel has emerged as one of the better prospects in the farm system. He's with the Pirates for the September stretch run and is our subject for today's Prospect of the Day.

Pimentel was signed by the Red Sox out of the Dominican Republic in 2006. Signed for just $25,000, he didn't throw particularly hard but showed good command, posting a 2.90 ERA with a 60/22 K/BB in 62 innings in the 2007 Dominican Summer League, followed by a 3.14 ERA with a 61/17 K/BB in 63 innings in the 2008 New York-Penn League. At this point, his best pitch was his change-up, while he worked to refine his curveball and gain more consistent velocity with an 87-90 heater.

He had a solid 2009 campaign for Low-A Greenville, with a 3.82 ERA and a 103/29 K/BB in 118 innings, although 135 hits was a lot. Still, he threw strikes, and he was beginning to gain size and strength. Moved up to High-A Salem for 2010, he posted a 4.06 ERA with a 102/42 K/BB in 129 innings with 120 hits. The Red Sox hype machine picked up on him and he started getting a lot of attention.

Pimentel opened 2011 with Double-A Portland and completely fell apart: he posted a 9.12 ERA, went 0-9 in 15 starts, with a terrible 30/23 K/BB in 50 innings and an ugly 75 hits allowed. Interestingly, he was throwing harder than before, up into the mid-90s, but his change-up regressed, and his curveball was so bad he junked it in favor of a slider/cutter, which wasn't much better.

He was demoted to High-A Salem at mid-season and improved somewhat, with a 4.53 ERA and a 35/16 K/BB with 50 hits allowed in 52 innings, but scouting reports from non-Boston sources were lukewarm at best. His mechanics had taken several steps backwards, and he looked like a real mess.

The Red Sox sent Pimentel back to Portland for 2012. He was okay, in comparison to 2011 at least, posting a 4.59 ERA with an 86/42 K/BB in 116 innings with 115 hits. Nothing great, but at least his ERA was below 9.00. He was up to 97-98 in short stretches and worked consistently at 92-94, but his change-up hadn't regained all of its previous quality and his slider/cutter was just so-so. It was no surprise when the Red Sox traded him.

With his new organization in 2013, Pimentel looked better in spring training. He was decent for Double-A Altoona, with a 3.61 ERA and a 61/35 K/BB in 77 innings. The ERA was better than last year, but his component ratios didn't really change much and his FIP was actually worse than what he posted in '12. However, Pimentel continued to throw well after moving up to Triple-A Indianapolis, posting a 3.13 ERA with a 62/21 K/BB in 92 innings. Overall he has a 3.35 ERA with a 123/56 K/BB in 160 innings this year.

Listed at 6-3, 230 pounds, Pimentel was born on February 1, 1990. Although his ERA is prettier, his numbers this year are actually very similar to 2012 in component terms: his K/9 went from 6.7 to 6.5, his BB/9 from 3.3 to 3.0; both changes are well within the possibility of random variation.

That's a caution flag, but the scouting reports are more enthusiastic: he is showing better command of his fastball, and his slider and change-up are more effective than they were in '12 and (certainly) '11. His delivery is more consistent and he isn't overthrowing, generating his velocity with less effort and keeping his mechanics in gear more frequently. He's still up to 95-97 at times but uses it better, and can dial the fastball back for less velocity but greater movement when he wants. Eastern and International League observers argue that the change of scenery suited him well.

The Pirates are using him in the bullpen for September. It remains to be seen if relief or the rotation is his long-term role, but his chance to have a role at all certainly looks better than it did two years ago. He could be a solid number three starter with further refinement, or failing that, a useful bullpen asset.