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Edwin Jackson’s Changeup Doing Him No Favors

Last night Edwin Jackson experienced the worst start of his career. It isn’t particularly close, either. The 10 runs he surrendered in just 2.1 innings trumps his next worst start, his final one of the 2009 season, in which he allowed eight runs in five innings. While it’s almost certainly an aberration, his start did continue a trend that we’ve seen so far this year from Jackson. He has started employing his curveball and changeup more often.

Just last year, as Dave Allen noted, Jackson used his slider more often than he had in years past. After throwing the pitch 22.5 percent of the time in 2007 and 20.6 percent in 2008, Jackson threw 25.5 percent sliders in 2009, the year in which he pitched more than he had previously in his career. Since Jackson is primarily a fastball-slider guy, he ended up going to the fastball more often, but also lessened his reliance on his third pitch, a changeup that hasn’t served him well in the past three years.

Last night Jackson threw 55 pitches. While he used his fastball a bit more often than he had in previous starts, he also used his changeup and curveball more often — and used both more often than his slider, which he threw just four times. Neither the curveball nor the changeup helped him much, as the results make clear. In fact, all three secondary pitches failed Jackson in the first inning. On an 0-1 count to Troy Tulowitzki Jackson threw a curveball low and in, and Tulowitzki lined it for a double. The next batter, Carlos Gonzalez, saw a 1-1 curveball below the zone, but he ripped it down the line for a two-RBI double. Jackson then went to his bread and butter, the slider, on the first pitch to Miguel Olivo, but left it up in the zone. That resulted in a ground rule double.

This increased use of his curveball and changeup was not a one-start occurrence. Maybe he used them more often because he wasn’t feeling the slider — he threw it four times and the results were double, foul, double, swing and miss. But the trend has spanned his five starts this season. His changeup use has increased from 6.6 percent in 2009 to 9.4 percent so far this season. His curveball rate has increased even more, going from 2.3 percent to 7.4 percent. While Jackson might benefit in the long run by adding two serviceable pitches to his repertoire, he still has some work to do with them.

The biggest problem with his increased changeup and curveball usage is that it has taken away from his best pitch, the slider. According to pitch type values the slider was by far his best pitch in 2008 and 2009. His curveball also proved a weapon in 2009, so perhaps working it in more frequently would be to his benefit. His changeup, though, has never been a good pitch, ranking in the negatives every year since 2007. It has been a particular disaster this year, yet he uses it more than his curveball, a pitch that appears to be better.

The one major complication I can think of in this case is employing dual breaking pitches. While his slider and curveball might be superior to his changeup, I imagine the stress on his arm is far greater when he throws the former two pitches. The change, then, might be a necessary evil, a different look that can help preserve his arm. Given how poorly he throws it, though, maybe he should go to it less frequently.