Lots of heated analysis on AN of why Trevor Cahill -- sorry, All-Star Trevor Cahill -- is pitching so much better this year. Fangraphs, giving the best numerical data it can, assesses the changeup as less effective when thrown compared to the sinker and curve.
I'm reminded, however, of Keith Foulke's comments when he was in his prime throwing a devastating changeup along with a 93MPH fastball he could locate. Foulke said that often, knowing that the changeup was in the back of the hitter's mind, he would throw nothing but fastballs in an entire at-bat. Fangraphs, of course, would only be able assess the effectiveness of the fastball during that at-bat, since that's the only pitch that was thrown. But make no mistake about it, the changeup had a lot to do with how effective the fastball was.
Even if Cahill isn't getting as many outs on the changeup itself, he is keeping hitters honest by having it as a real weapon in his back pocket. Hitters are not handling his sinker as well or reacting to it as quickly, and they are not able to sit on a pitch because Cahill is now a true 3-pitch pitcher (sinker, change, curve) who does not get into a pattern.â†µ
A pitch can be a huge weapon even in between the times it's actually thrown.â†µ