I think he's hit that magic "Innings Pitched" number where a talented pitcher puts talent to better use through the knowledge he's learned over his first 3-4 years of getting beat up by the league (look at guys like Mac Suzuki of the Royals who has the ability to hit 95 and has a very good splitter for an out pitch but can't even make it as a set-up man because he just hasn't figured out how to use those two pitches effectively).
I thought about that, but still went with Fick. Weaver is much improved, no doubt, and a workhorse. But his ERA is only OK, not great, and he does have that losing record. But I wouldn't object if Weaver is the Tiger chosen--especially if he throws another shutout or two, like he did the other night.