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Jack Cust’s New Approach at the Plate

Jack Cust came into the season looking to cut down on his strikeout numbers, and he has done just that from 2008’s 41% K/AB to 30% K/AB this year. Unfortunately his BB/PA and HR/FB rates have also dropped (19% to 11% and 30% to 15% respectively). Put that all together, and add in a meager .273 BABIP, and you have a 0.324 wOBA. Down considerably from 2007 and 2008.

A week and a half ago Eric warned us about trying to create reasons for small sample shifts in performance. Over even half a season’s worth of time a good player can put up poor numbers, not because of any shift in true talent or changing approach but just because the coin lands tails a few too many times.

In this case, though, I think we can attribute some of the shift in Cust’s numbers to a change in approach. To begin with we were warned of the change in approach BEFORE we saw the shift in numbers. Also the shift is reflected in the more granular pitch-by-pitch data, although these are not immune from small sample size variation either. Last year Cust swung at 38% of the pitches he saw, in the bottom five, this year it is 45%, just a shade under league average. That is a huge shift, and he is seeing fewer pitches inside the zone this year than last.

I wanted to see where these additional pitches he is swinging at were. So I plotted all of the pitches that he took and swung at and then drew contour lines at the 50% break. Effectively inside the contour line he is more likely than not to swing at a pitch and outside less likely. Here are his contours in 2008, 2009 and for all lefties.


Cust’s additional swings are coming everywhere, inside, outside, low and high. He has added area inside the strike zone (which is good), but also area outside the strike zone (bad). In addition, it looks like Cust is now a freer-swinger than the average lefty. His swing rate is lower than average, but once you correct for the location of pitches seen he swings more often than the average lefty.

Additionally his contact rate is up, but power down. So it looks like Cust is swinging less hard (more contact less HRs) at more pitches. Athletics Nation noted the shift in numbers and suggested that Cust should go back to taking the 07-08 Cust approach at the plate, I would have to agree.