The Brewers have one quality starting pitcher. If they don't trade for another one (Peavy?), there's no way their pitching staff will hold up. The Tigers right now have got a very strong pitching staff, and they have a decent pitcher in Bonderman waiting in the wings. Oh, and if the Sox could play the Pirates 17 more times this season, I'd say they'd have a better chance at making a run.
Also, the Cardinals are a much better candidate to win the NL Central than the Brewers. Have you seen the Brewers offense since Weeks went out? Hopefully Carpenter and Wainwright can stay healthy, and Ludwick/Ankiel return.