Pimentel was signed by the Red Sox and began his career pitching for their Dominican Summer League team in 2007. He started 13 out of 14 games, finishing with a 3-1 record and a 2.90 ERA. At age 17, he yielded only 44 hits in 62 innings. He walked 22 and struck out 60, leading to a 1.06 WHIP. Boston had uncovered a fine young arm with huge upside.
His career was moving along nicely in the Boston organization until he hit some speed bumps at Double-A Portland. His walk and hits-per-inning rates increased. In the 2012 offseason, the Red Sox traded Pimentel to the Pirates, along with pitcher Mark Melancon, outfielder Jerry Sands and infielder Ivan De Jesus, for pitcher Joel Hanrahan and infielder Brock Holt.
Pimentel remained a starting pitcher through last season, when he made 27 starts combined for Double-A Altoona (13) and Triple-A Indianapolis (14). He had a combined 3.35 ERA over 169 1/3 innings. He walked an average of three per nine innings, while striking out a bit more than six per nine. Using a good variety of pitches, Pimentel yielded only 150 hits.
The Pirates promoted Pimentel to the Major League club for a brief look in September last year. He pitched in five games out of the bullpen, finishing the season with a 1.93 ERA over 9 1/3 innings.
Pimentel began the 2014 season with the Pirates, but he missed some time with a shoulder injury in May. He returned to the club in mid-June after a Minor League rehab assignment. Again, he was assigned to pitch in relief.
Pimentel has the type of stuff that could allow him to move to the Pirates' rotation at some point. He has always had the type of fastball that can set up the rest of his repertoire. He usually sits between 92-94 mph with that pitch, but he can hit 95 mph with little effort. His fastball is effective in setting up his slider/split as his "out" pitch. That's the combination I saw him use when he pitched in relief against the D-backs.
While I have seen Pimentel throw an effective changeup in the past, when he works out of the bullpen, he seems to rely heavily on getting ahead in the counts with a sinking fastball that has lots of late life while he works his slider down and away from right-handed hitters. This season at the Major League level, ironically, left-handed hitters are struggling against him, while right-handed hitters are having success. They have hit some home runs off elevated pitches. As a matter of fact, he yielded a home run in a game I saw with a pitch that hung in the zone and didn't sink.
More than likely, erratic command may be the factor keeping Pimentel from joining the Pirates' rotation. He doesn't always repeat his delivery, losing rhythm quickly at times but having the ability to recover before allowing too much damage. Like all pitchers, control will dictate his success and probably his pitching future. If he gets ahead in counts and controls at-bats, Pimentel becomes very tough to hit. His control looked good in the outing I saw in Phoenix.
Looking ahead, Pimentel's value should remain high as he's still learning the finer nuances of pitching. His youth, his strong frame and his power arm bode well for versatility from a pitcher who has the ability to pitch in relief or eventually join the rotation.