Anderson Used to Shift His Position on the Mound

We here at Fangraphs are big Brett Anderson fans: Dave Cameron has a huge crush on him; I fawned over his crazy slider; Marc Hulet saw him as the AL ROY favorite last August and then was devastated when he missed out on him in his fantasy auction; and, RJ Anderson and David Golebiewski see him as one of the game’s top starters. So when a commenter to my post last Thursday on Sheets shifting his position on the mound noted that Brett Anderson used to do this too, I jumped at the opportunity to check it out.

In this image I plot the histogram of his horizontal release points versus RHBs (solid) and LHBs (dash). In April and May he had two clear release points: one to RHBs and another shifted to the extreme arm-side of the mound to LHBs. But starting in June and continuing for the rest of the season — and in his starts so far this season — he uses a single location on the mound, the one he had previously used just to RHBs. On the right side of the graph it shows the number of Ks and BBs he had that game. (There is no pitchf/x data for his April 28th start.)

We all know that correlation does not equal causation — so we cannot say that Anderson started doing better because he stopped using two different positions on the mound — but it is interesting that at the same time he dropped the second position on the mound he also started pitching much better (FIP of 5.88 in April and May versus a FIP of 3.04 from June on).

Dave Allen's other baseball work can be found at Baseball Analysts.

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Maybe you meant to say correlation does not equal causation?