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Grady Sizemore’s Plate Discipline Problems

Between 2005 and 2008, Grady Sizemore was, by our WAR valuation system, the fourth best position player and one of just four worth over 20 wins. Last year he had an injury-shortened, down year — though was still worth almost two wins — so this year he was looking to reestablish himself as one of the game’s elite players; at this point, that has not happened.

His wOBA sits at a disappointing 0.264. In 119 PAs he has yet to hit a home run. His strikeout rate is at an all-time high, while his walk rate and ISO at all-time lows. The plate discipline issues problems seem particularly troubling. Over his career Sizemore has had great plate discipline numbers, but this year Sizemore is swinging at 32% of the pitches he sees out of the zone. His career average is 19%, and his previous high is just 20%. On the other hand, he is swinging at fewer pitches in the strike zone, just 59% compared to a career average of 65% and a previous low of 63%. So it is not that he is just swinging more at all pitches, rather he is swinging at more pitches he shouldn’t and at fewer pitches he should. That is what leads to his career-high K rate and career-low BB rate, and probably plays a role in his power decline.

Using the pitchf/x data I looked at his swing rate broken up into bins by pitch location. Then I looked at the change in swing rate for each location between this year compared to 2007-2009 (the years covered by the pitchf/x data). Red locations have a higher swing rate in 2010, while blue a lower swing rate in 2010. The color intensity represents the magnitude of the difference.

Since he has only seen 470 pitches this year the data are a little noisy, but you can see a clear trend. Locations outside the zone have a higher swing rate, particularly on inside pitches, while those in the zone, particularly down-and-away, have a lower swing rate. So the pitchf/x data support the BIS plate discipline numbers, and they are troubling for Sizemore and the Indians.