It's not really that "curious" though, not in a negative way. If he is good, then he'll be an absolute steal. If he's not, then they lose but not that much. The deal has a lot more upside than downside for the Tigers. I think it's the kind of thing that a mid-market team needs to do if it wants to be able to keep good players for a long time.
For Keith, he'll will be set for life even if he fails. If he is good, he'll lose a lot of money,but he'll still be young enough where he can sign a good free agent deal later.