In Jake Arrieta’s first start of the 2017 campaign, he averaged 90.5 mph, down from his typical 94 mph average. Even more unsettling, the switch to Trackman data means the 90.5 MPH average might have read like 89.5-90 mph with PitchFX tracking. It’s possible the bearded Cubs pitcher was essentially throwing over 4 mph slower in his first start than he was last season.
To preface, let me say that I’m skeptical about his data from Busch Stadium. The tracking was very spotty and only half of Arrieta’s pitches were recorded for some reason. However, Adam Wainwright was throwing faster against the Cubs than his typical average, suggesting velocity measurements might have been okay. Still, Trackman might’ve had difficulty picking up Arrieta’s velocity because of his unusual release point.
Even with all these issues in mind, I think it’s worthwhile for us to look at why he might have been throwing slower.
Here at Cubs Insider, we’ve talked about Arrieta’s release point inconsistency in great detail. His struggles last year can be largely attributed to an inconsistent in-game release point, which affected slider movement. As such, we’ve got a useful marker when trying to project future performances.
Arrietea’s release point inconsistency was once again an issue Tuesday, but the point at which he let go of the ball was drastically different from years past, as seen below. The first graph is his horizontal release point, and the second is his vertical release point. Pay no attention to the the games on the X axis; the far right dots are from St. Louis, though the game is not explicitly stated.
Arrieta let go of his slider and sinker 0.25-0.5 inches lower and the same distance closer to the third base side against the Cardinals. In general, his motion was almost reminiscent of a 3/4 slot.
Perhaps this change in release point is to blame for slower velocity. These changes aren’t necessarily bad in a vacuum, but they could be detrimental in this case if the drop in velocity is a real thing. Before we hit the panic button, though, let’s see what his velocity looks like in a full game under the watchful eyes of Trackman cameras.