Couple thoughts that I haven't seen brought up yet...
1) Sheff is a righty... Tigers needed lefty bats last year so it doesn't fill that need althought he immediately becomes their best right handed hitter...
2) SANCHEZ *INJURY* is what kept Tigers from dealing him to Washington for Soriano... Once Sanchez missed that infamous start in Toledo, Washington backed off... Sanchez when on the shelf briefly, came back and hurt the same elbow...
Moral of the story, I think the Tigers knew more about Sanchez's medical history (and tapped his future as questionable) than they let on ... this is the same organization that let John Smoltz go for Doyle Alexander... they won't repeat that mistake again.
As for Sheff's "clubhouse" issues - Leyland was happy as a pig in slop... he's a large supporter of Sheff and will surely keep him in check in the clubhouse... The Tigers clubhouse was very happy go lucky last year - IRod, Mags, and the like all got along because Leyland changed the attitude... there were never any problems in their clubhouse last year.