Dude, John Galt, don't drop Stewart. He will be great, but is just going through a big slump. He is a winner though, acknowledges the slump, and will be back.
Remember that he got nothing but rave reviews from even Helton, et al, in Spring Training. In fact, I would watch out for people who are trying to buy low on him (or even worse, people who are waiting to pick him up from free agency).