After two seasons and 168 innings split between two-leagues in the Mets system, Deolis Guerra had compiled a decent peripheral set - averaging 7.3 strikeouts per nine innings while walking 3.6 per nine. Once with the Twins organization, the team assigned him to Fort Myers (HA) where, at 19 years old, Guerra was nearly three years younger than his competition last year. In 2008, his third stint in the Florida State League, word trickled in that his fastball had lost a few MPHs and his control vanished. In what was his worst month, Guerra threw 23 innings in August and issued 20 free passes. Not surprisingly, his overall walk rate ballooned (4.9 BB/9) while his strikeout rate shrank (4.9). Reports of Guerra's reduced velocity and sub-par peripheral numbers conjured up collective groans from Twins territory as the budding pitching prospect acquired for Johan Santana trade seemed like it it was heading for another prospect miss.
However, beginning 2009 with his fourth tour of duty in the FSL, Guerra showed signs of progress. His strikeout rate, albeit still below the FSL average of 7.3, was an improved 5.8 K/9. Additionally he was able to shave off several walks, dropping his rate to 2.5. This development earned him an advancement to AA New Britain on July 7th. His relocation to the Eastern League brought out the best of the big righty. In his July 23rd start against hte Portland Sea Dogs, Guerra struck out 12 in seven innings and earned the Eastern League's Pitcher of the Week award. In his most recent start, Guerra flirted with a no-hitter, actually not allowing a hit to the Akron Aeros for six innings and striking out nine before being lifted for a relief pitcher.
Where did this monster come from?
Normally in order to figure out what has changed I'd pour over pitchf/x data or the Inside Edge database attempting to find some answers to Guerra's improvement. Maybe he regained velocity, changed arm motion, mixed in more breaking balls, etc. Unfortunately these methods are unavailable when looking to analyze minor league talent. Instead I wander through the few available youtube clips of Guerra and tried to breakdown his mechanics between the two seasons. Dissecting video contributed to the Internet by the now-defunct SaberScouting from 2008 of Guerra's performance in Fort Myers in comparison to Guerra's New Britain performance supplied by TwinsonTwins.blogspot.com we can identify several items that he has refined in his mechanics that has led to this improved execution.
The first thing that should jump out to you about the two motions is how stable Guerra is in his 2009 mechanics (bottom-white-uni) comparative to 2008 (top-greys). Guerra's movement appears more fluid and steady this season. Last year's model on the other hand contains some heavy herky-jerky actions. This stems from his days in the Mets' organization, when Guerra sped through both the system and his delivery; neither of which were very good for him as a young pitcher. The Twins set out to regroup his delivery and get him back under control.
One of the most identifiable differences in his two deliveries - or at least the one the eyes focuses on first - is his leg-kick. In 2008, his leg-kick had more of a pronounced pendulum swing appearance about it before bringing the leg up to where the balance point should be. Because he is not bringing up his leg in a controlled manner, the extra movement prevents him from getting to a collected balance point to drive off the rubber. Due to this inertia in his lower-half, his upper-half must counter to achieve a state of equilibrium between his lower and upper extremities. Guerra forced his top-half to do an over-exaggerated wrap - a process where his back rolls to the point where he is showing the hitter both digits on his uniform. This contortion causes his shoulders to rotate off the second-home line and onto the east-west axis, where they are almost parallel with first-third (but more appropriately, the second baseman and third base line). This season, Guerra has implemented a more 'contained' and deliberate leg-kick, the lift of which looks more intentional rather than a someone doing an impromptu Rockette's routine. He still brings the front leg close to his chest to derive power from, only Guerra is in far better control of his actions, keeping his lower and upper portions in unison.
Once he twists his upper body off of the driveline, Guerra would need to re-adjust his motion to direct his momentum to the batter. This resulted in another problem in Guerra's 'long-arming' the ball:
Although these two videos are shot at slightly different locations above the left-handed batter's box (and set at a slightly different pace), you can clearly see that Guerra's arm in the top clip reveals Guerra reaching back further - almost dipping his back shoulder - in last year's model prior to coming forward with his delivery. In addition to that, Guerra's elbow is wandering in some fairly uncharted territories. It takes a substantial amount of effort to get his pitching arm righted once it wanders off this far. Furthermore, Guerra's 2008 arm action gives the hitter several more reference points to pick up the ball and time him better whereas this season Guerra seems to hide the ball a bit better (even though you can pick it up for a brief moment behind his back).
Guerra's newly stabilized mechanics undoubtedly play a significant role in both his increased velocity and command of the strike zone. Because he is still just 20 years old and playing in a league that is nearly five years older on average, it would be best to see Guerra repeat AA New Britain in 2010 to ensure that his mechanics remain consistent and avoid regressing into bad habits before advancing to AAA Rochester.
A special thanks to the guys at twinsontwins.blogspot.com who have been posting the New Britain footage on youtube. I encourage you guys - as well as anyone else that has access to a camera and the farm system - to keep the clips coming onto youtube!