I don't think you can put down the BABIP issue to just one thing or another...
He averages around a .250 BABIP, over the last five years. He hits more fly balls and more pop-ups than the average player, and, because his ambition when he swings is dialed up to 11 on the dial, his fly balls are often "got under it" fly balls...lots of flyouts and pop-ups not well struck or struck hard but with a launch angle that is too high. On top of that, he is a VERY extreme pull hitter, so when he does hit it on the ground, he is hitting into the teeth of a very confident shift. And...as a third factor, his BABIP will be lower in a homer-friendly park like Skydome because the balls he does nut up leave the yard more often than they would at Safeco, where they turn into doubles.
And...for one final factor...he's not particularly fast.