All the talk about the numbers Anderson would put up if he was playing full time is well and good... but he's not going to be getting full PT (at least for some time).
Thames wasn't the full-time designated hitter in the wake of Gary Sheffield's release, and with Thames now out, the Tigers aren't going to rely on one player to replace him, either. The loss likely accentuates Leyland's efforts to rotate players in and out of the DH slot to get them rest. Magglio Ordonez started there on Wednesday, while Ryan Raburn arrived from Triple-A Toledo in time to start in right field.
"I can go a lot of different ways with it," Leyland said, "which is why we opened it up."
Leyland seems to have gotten really stuck on keeping Guillen in LF for some reason, although for the life of me I can't figure out why. He can't be that much of a better defender than Larish, Raburn, or even Thames, and he's not even close to Anderson.
My personal thoughts would be to put Anderson in for a couple of weeks to see if he's going to hit major-league pitching consistently. If he does, there's no reason why he shouldn't be your everyday LF (with Guillen DHing). But, Leyland apparently has other plans, as he always seem to.
I'd figure Anderson may get an extra 10 ABs while Thames is out for the next couple of weeks. That's it. He'll still be getting 1/3 of the LF time, splitting with Guillen/Larish and the DH spot getting split between Guillen/Magglio/Larish.