I'll repeat my Baez take...he can't be the focal point of your team. He was perfect on the Cubs where he could operate behind a lot of other guys. The Tigers miscalculated that they were close to 'contention' and signed him as an alpha star.
But he can still be a decent player with all of the flightiness and free swinging. This is why you sign the top free agent, not the 4th best.
For some reason, Ilitch and Avila wanted to sign a guy before the lockout. This is the result.