Ariel Pena K's Cal League: Top Angels Prospect Performances of 2011

7) Ariel Pena, 05/20/1989 -- rhsp, High A and AAA

10 wins, 6 losses. 163 IP, 4.39 ERA, 166 hits and 196 K/87 BB. 6 runs saved, 3.4 WAR

Pena received some attention after his stellar 2008 Dominican Summer League campaign, when he put up video game stats as co-ace of an outstanding rookie league rotation that also included Fabio Martinez Mesa and Orangel Arenas. He put up good but not great numbers stateside in 2009 and 2010, showing a propensity to strike guys out at an above average rate, but yielding too many walks and hits.

In 2011, Pena's K-rate jumped to over a batter an inning on the strength of what 66er's broadcaster Sam Farber routinely called the "best fastball/slider combo in the California League." While I'm not sure that was strictly true, Pena did pace the California League in punch-outs, and capped the season with a dominant playoff performance where he fanned thirteen in just over seven innings. While his walk and hit rates were again mediocre (1.54 WHIP), limiting his overall effectiveness, the improved K-rate has elevated Pena to one of the more interesting Angels' prospects.

Pena works in the low 90's and hits 95 with his fastball. Despite coming out of a low-ish three quarters arm slot, the heater doesn't have much lateral movement, though it does have enough late life to give hitters a difficult time up in the zone. While he showed slight groundball tendencies in 2011, he tends to elevate the FB, inducing some swing and miss but also missing his spots enough to give up plenty of hits. Predictably, fastball command was Pena's Achilles heal when I saw him pitch in his lone AAA start this year: when he hit his spots, primarily working up and away from hitters, he looked great. But when he began to overthrow, he lost control of his mechanics, and the wheels came off the bus.

His best pitch is his slider. It's a sweepy bender with big-breaking shape, though the Angels will probably want him to "tighten the pitch up" as he advances through the system. From the fan's standpoint, that means that the slider may actually look less impressive a year or two from now because it will lack its current, easily visible break away from a right-handed batter; but it should also mean that advanced hitters will have a harder time identifying the pitch early in its trajectory, leading to better results. Think Ervin Santana's slider - at its best, it's one of the more effective breaking balls in the league because hitters have such a difficult time distinguishing it from his fastball, but the short, violent tilt at the end of its trajectory isn't as obviously impressive as a sweepy, less refined breaking ball. Tweaking the pitch will be important, because even Pena's stand-out slider failed him against AAA hitters.

After temporarily losing the ability to throw his fastball for a strike in his lone Salt Lake game, Pena walked a hitter, then fell back on his slider because he could still get it over the plate. Ex-major leaguer Jorge Cantu hung in against the pitch, chipping a few away, albeit with ugly swings. But then Cantu recognized the pitch early enough to slow his bat down, and he lined the fourth slider of the AB into left for an RBI single. I doubt many single-A hitters had been able to do that against Pena, but major leaguers will be. Undeterred, Pena came right back with the breaking ball against the next hitter, but the opposition was now sitting on the pitch, and he got pounded. Pena wound up yielding seven hits and four walks in just four innings against the more advanced competition.

So far, Pena lacks a credible third pitch, which puts him at a disadvantage against lefties, who hit .292 against him while walking at a rate of almost a batter an inning. He needs to develop that change-up, because it's presently not doing much for him. If he can't do that, he's likely headed to the bullpen.

Pena's mechanics also appear to be holding him back. Back in instructional league in October of 2010, his delivery looked both deliberate and consistent (you can check him out at Stephen Smith's outstanding video gallery at www.futureangels.com). However, in his August start with the Bees, consistency deserted him. He noticeably stabs the ball down and away in his back arm action, which may help him to stay back over the mound, but it also means that he drags his arm a little and tends to pitch up in the zone. When I saw him, his delivery got out of whack when he overthrew in the second inning: he got overly rotational towards his glove side, flailing around in his follow through. I imagine that the Angels will push him to stay more in line with the plate to maintain fastball command.

At 6'3", 183 lbs, Pena has the classic pitcher's frame and some more projection remaining, meaning that his fastball could still gain a tick or two of velocity as he fills out and gets stronger. Combine that with his impressive K-rate, the quality of his breaking ball, and his fine 2011 season in the difficult California League, and you have a guy worth paying attention to. I don't view him as an elite prospect quite yet, but if he takes another step forward in 2012 like he did in 2011, he will certainly be in that conversation.