To be fair, if you're a pitcher it's a helluva lot safer to pound the strikezone against the Cubs' lineup than the Yankees' or the Red Sox'. Looks like a little of both: %St %O-Z %SwO-Z PPA
Yankees 44.1 55.9 26.7 3.95
Bsox 44.9 55.1 28.7 3.98
Cubs 46.2 53.8 31.7 3.76 Those numbers only include the top 8 players, PA-wise (This is in order to negate the effect of pitchers hitting, although taking the numbers for the roster as a whole reproduces very similar results). It appears that the Yanks and Sox see a few less pitches in the zone (St) than out of the zone (O-Z), but they also swing at fewer pitches outside the zone (SwO-Z) and see more pitches per PA.