A lot went wrong for Shin-Soo Choo in 2011. Injuries and a DUI may have contributed to his struggles, but from Opening Day he simply looked like a different man at the plate.

While Choo’s stats declined across the board, the most noticeable difference was in his power numbers. From 2009-10, Choo averaged an extra-base hit once every 9 at bats. In 2011, he went for extra bases just once every 14 at-bats, and homered just once every 39 at-bats.

Such a dramatic decline doesn’t happen due to bad luck, so what exactly led to Choo’s power outage?

My first instinct was that something must have happened to Choo’s bat speed, which is often a contributing factor to a decline in power. This typically manifests itself in a decline in production against fastballs, but that wasn’t the case for Choo. His slugging percentage versus fastballs dropped only slightly, and against lefties – where one would expect to see the most trouble – his slugging percentage versus fastballs only dropped by .001.

So if he can still hit the fastball, then it must be the offspeed stuff.

After analyzing Choo’s numbers against various offspeed pitches, it became clear that he suddenly developed an irrational fear of sliders.

In 2010, Choo hit .308 (24-78) with nine extra-base hits (four doubles, five home runs) against sliders. In 2011, those numbers decreased to .169 (10-59) with just one extra-base hit (a triple).

Isolating Choo’s struggles to his performance against one pitch may seem like an oversimplification of the problem – and it’s true, his numbers in other situations dipped slightly as well. However, in no one area did his numbers decline so dramatically.

If you alter Choo’s 2011 stats to reflect his 2010 performance against sliders (appropriately adjusting for the decrease in total plate appearances) his numbers dramatically improve. And while they don’t quite match his impressive 2010 numbers, they at least start to resemble the Choo we expected to anchor the middle of the Tribe’s order.

2011 Actual Stats
2011 Stats w/ 2010 Slider stats
2010 Actual Stats

To further demonstrate Choo’s struggles with the slider, take a look at the heap maps illustrating his isolated slugging against the slider over the past two seasons.

It doesn’t get much more clear than that image. Choo was simply helpless against the slider.

So where does he go from here?

It’s tough to say what exactly led to Choo’s struggles against sliders. Nothing in his past indicated that he was vulnerable to the pitch. And, as a result, it’s tough to prescribe a quick fix.

The only thing we can do now is be patient and see what happens. This will definitely be a stat to keep an eye on early in 2012, and could be one of the keys to the Tribe’s offensive success.

Follow Ryan on twitter @TribeFanMcC

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