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.

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

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14 years ago

So Cust tried to cut down on his strikeout rate by expanding his zone? What genius recommended that? Now reducing/shortening his swing could certainly reduce his strikeout rate and his power, but he should have left his zone the way it was.

14 years ago
Reply to  mymrbig

Bob effin Geren.

Don’t worry, though… Im sure he’s not long for the job.

14 years ago
Reply to  alskor

Unfortunately, if Billy Beane were of the mind to fire his best friend, he would’ve done it two years ago when it was painfully obvious that the man was in over his head. He’s not Trey Hillman bad, but he’s pretty freaking terrible.

14 years ago
Reply to  mymrbig

Also does his strike zone look different on different pitch counts? It would be interesting if he had a similar approach on counts where he was ahead but switched to this expanded zone strategy once he falls behind or has two strikes on him.

In other words : Be selective and swing hard when you have the advantage but shorten your swing and swing more to avoid called strike 3s.

14 years ago
Reply to  Craig

But that’s exactly the problem. He’s swinging at more close third strikes, still missing them, but not drawing walks. He’s hitting more weak fly balls and walking less. This Cust season is proof positive that striking out is no big deal if you do the other things he does/did well.