Last season, the switch-hitting Alexi Casilla had produced at a very good rate against right-handed pitching.

In 247 plate appearances in the left-handed batter's box, he hit .274/.350/.400 – not too shabby for a middle infielder. This was a significant improvement for someone who had hit .228/.299/.320 from the left-side over the two previous seasons (2009 and 2010) in 314 plate appearances.

Most analysts would likely dismiss his 2011 breakout as a statistical glitch of the effects of a small sample galaxy in comparison to his vast universe of career suck-i-tude. Meanwhile, before this season started I presented the argument that Casilla, at the ripe baseball age of 27, was finally ready to breakout. Based upon his mechanical changes he made in 2011 and his impressive winter ball performance which yielded some very good numbers, I was optimistic that Casilla would more than earn his $1.4 million payday and pick up where he left off in July of 2011.

Of course, rather than being motivated to prove my thesis correct, Casilla continued to do his best Luis Rivas impersonation.

After posting a career-best 750 OPS against right-handed pitching in 2011, Casilla has struggled to even reach 500 mark (currently at 475 OPS). In fact, his .192 average against right-handers is the fourth-lowest in the American League and the lowest among those with the platoon advantage. Once again, although it may be easy to simplify his performance to regression, Casilla's offensive downturn has more to do with his mechanics and timing.

The first clip is a swing from June 2011 that exemplifies his approach from May through July of 2011. Watch his lower half and witness a fluid and unison leg lift, a front toe tap that comes after the pitcher releases the ball and a noticeably violent lower-half weight transfer:

Casilla implemented these mechanics from May onward of last season and experienced terrific results. This gives his swing pop, instead of the slap-hitting Casilla we became accustom to seeing over the majority of his career.

Compare that swing to his pre-May 2011 approach:

Notice that his stride is completed prior to the pitcher's release of the ball (in the first version, he started his stride mid-pitch), leaving him flat-footed and simply shifting his weight from back to front and using more of his upper body in his swing.

Casilla's current mechanics are almost identical to those he used before his hot streak in 2011. Note the foot plant well before the pitcher's release and muted weight shift:

There is no clear reason as to why Casilla abandoned the method which proved the most fruitful for one that is quickly expediting his career out of professional baseball. Perhaps it is that his sporadic time between starts has thrown off his timing. Maybe it is something that the coaching staff has encouraged him to revert back to the old approach. Whatever the rationale behind it, it would seem to make more sense to attempt to revisit video of his swing from last year and attempt to resurrect his mechanics from that stretch of baseball.

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