Chris Carpenter has some pundits and fans scratching their heads this year: How can the Cardinal ace be allowing so many hits? Why does he have such a bad ERA? What’s wrong with him?
Perhaps nothing is wrong with him (other than some minor effects of aging). True, he is yielding hits at a 10.9 per nine innings clip, easily his highest as a Cardinal in a qualifying season. But for those unfamiliar with the concept of defense-independent pitching (now celebrating its 10th anniversary!), “There is little if any difference among major-league pitchers in their ability to prevent hits on balls hit in the field of play.” Therefore, we need to be careful in ascribing too much of that hit rate to Carpenter.
Consider the level of Carp’s BABIP this year. It’s at .338, whereas his career rate (more in line with most pitchers) is .297. Two factors appear to be responsible for this.
First is the category of defense and “luck.” And in this, we see that the Cardinals as a team are below average, which affects their entire pitching staff, though it might affect some more than others. They’re 10th in the NL in Defensive-Efficiency Rate (DER), which measures the rate at which defenses convert balls in play into outs (the Cardinals were 7th and 5th, respectively, in 2010 and 2009).
Something that Carpenter does have some control over is his groundball rate, which is about 6% lower than his career rate. That 6% is being reallocated, if you will, a bit as fly balls but mostly as line drives: His line-drive rate is up 5% over his career rate. That’s undoubtedly contributing to his hits allowed.
Combine that lack of defense with Carpenter’s uptick in line-drive percentage, and that pretty well explains the hit increase. Figuring out the increase in line-drive rate is a bit more difficult. All of his swing-contact rates are nearly what they were last year. The key may be that he’s throwing harder stuff more often and his curveball less — about 6% more fastballs and sliders. So it may simply be that batters are hitting more fastballs and therefore hitting them harder and more squarely than curveballs, which is turning groundballs into liners. Our suggestion? Carpenter should mix in more curveballs. As for the rest, pundits and fans need to realize that much of Carpenter’s performance rests on his defense, which is something that is out of his control.