He had a .219 BA against lefties. That is almost .100 less than against righties. That is "can't hit lefties" in my book.
Look at the Phillies line-up--Howard, Abreu and Utley, the meat of the order, are all lefties. If I am managing against the Phils in a close game, the middle of their order sees a lefty every time after my starter is out.
You could make the arguement that the more lefties Utley sees the better he will be able to hit them, but we don't know for sure that this will be the case. Just as likely he continue to have disparate RHP/LHPsplits and the opposition will key on this even more. This happened to Blalock.