I haven't been able to afford those bats yet, but given that ITP is based on the OOTP engine, and given that OOTP is known for its streaks and statistical variance, isn't the most likely answer that you simply, coincidentally, had a bad year right after buying the bat?
EDIT> Or, Orrie could say exactly what I said, only 2 minutes sooner, and make me look foolish.
