Ryan Dempster has not suffered a major velocity drop this April. He has not struggled to find the plate or strike batters out. The Chicago Cubs right-handed ace has 29 strikeouts and just 12 walks in narrowly more than 30 innings this season. His batted-ball distribution is nearly identical to the last two seasons.
Yet, Dempster’s ERA sits at 7.63 entering his sixth start of the season, in Arizona Thursday. He has given up eight home runs and roughly two of every five runners who have reached base against him have scored. Bad luck is definitely in play, but what else explains Dempster’s early scuffling?
It seems like his slider is slowly deserting him. Dempster had a strong spring, but in those contests one can get minor league batters out with sheer fastball location and guile. Now that the season has begun, hitters are teeing off on Dempster’s slider.
The pitch, as Dempster throws it, is a sweeping mid-80s breaking ball. The movement is deceptive without being biting or especially wide. He has long relied on keeping hitters off the pitch with a 91- to 93-mile-an-hour fastball and a split-fingered pitch. His famous glove waggle is a defense mechanism against pitch tipping, because Dempster’s success depends upon batters guessing wrong.
They have not done so in 2011. For the four prior years, the slider had been a devastating weapon for Dempster. This season, though, it has been the pitch on which hitters have gotten him.
|Year||Slider value (total)||Slider value (average run value/100 thrown)|
The problem may be deception, or it may be that the pitch has less tilt. Analytically, his slider has definitely trended toward horizontal rather than vertical movement. Comparing his 2010 and 2011 pitch mapping for movement, his sliders this season have drawn wider bands of lateral movement but much smaller ones of vertical movement within strike zone. Anecdotally, the pitch has repeatedly “flattened out,” as scouts say, making a number of those home runs (notably, an Opening-Day grand slam by Pittsburgh’s Neil Walker) possible.
Dempster still has the power on his four-seam and split-fingered fastballs to stick it out as a decent big-league pitcher. If the 33-year-old intends to live up to the billing he got when the Cubs gave him the ball on Opening Day, though, he needs that breaking ball to sharpen up, get down and induce swinging strikes. His depleted effectiveness with the pitch has led to substantial drops-off in chase rate, swinging-strike percentage and overall contact rates by opponents. He has been more aggressive, spiking his share of pitches within the strike zone by nearly 20 percent, but the reality is that he needs to hone his slider well enough to throw them away from right-handed hitters and out of the strike zone. In the meantime, his aggression is actually a bad idea.