I feel like it's definitely been a little bit expanded ... I understand that everybody has discrepancies, but you know when the strike zone's in question, sometimes you go up there and you chase pitches that you normally wouldn't ... It affects the way you approach the at-bats in the future. I found myself a lot of times chasing pitches that I normally wouldn't. ...Drew's on-base percentage this season is .351. It's the third lowest of his career and the lowest since 2002. Same thing with his .261 batting average -- third lowest of his career and the worst since 2002. His BB% is also lower than any season since 2002.
As a hitter, you're trying to get to 2-and-0 or 2-and-1 or 3-and-1 and get a good pitch to hit. ... When you start seeing those strike zones expanding, you're kind of questioning if you're wrong or right. You don't really know. The next thing you know, you're swinging at pitches all over the place. And that's not how I like to play the game.
The data at Fangraphs confirms Drew's statements about the changes he has made at the plate. His O-Swing% (the percentage of pitches outside of the strike zone that he has swung at) is way up this year. In his first three seasons with Boston (2007-09), it was 16.9%, 17.5%, 15.4%. In 2010, it is 20.4%.
Drew is also swinging at fewer pitches inside the strike zone -- so while he is swinging at roughly the same percentage of pitches, more of them are out of the zone.
Yet he is also making far more contact with pitches outside the zone than he ever has before. Again, from 2007 to 2009, it was 49.2%, 51.7%, and 59.0%. This year, it has shot up to 69.9% -- which is 18.5% higher than his career rate.
(David Ortiz's numbers are similar. He is swinging at far more pitches outside the zone -- his O-swing% has been rising every year since 2003, in fact, -- though he is offering at fewer pitches in general. Plus he is seeing fewer strikes than any season in his career.)
There must be a fair amount of pitches that, in the past, Drew would have been confident taking for a ball, but now cannot risk them being called strikes, so he's swinging at them. His adjustments have meant more contact on those pitches, but it has resulted in a lower batting average. And the fewer walks is causing a further drop in his OBP, as well.