It's been pointed out that Gata has been right about Vargas since the beginning of June. In June, he was ,208 / .212 / .229, and he's been worse in July.
Vargas is a limited player. A useful utility guy to give you some flexibility to pinch hit or pull guys from the field, and can cover when guys get ejected or hurt, and even give a day off. I like him in some offense situations, like when we need contact, but he's certainly fallen off lately. This will let Vargas do what he does best, which is come off the bench.
Trey is the every day 3rd baseman, probably until House or Morales is called up next year. As long as his arm is OK, his glove is fine, and he can spray the ball against overshifts in the infield.