Deal works for both Leyland and Tigers

The Tigers won the pennant. In those circumstances, the manager doesn't get fired. What is different about the Tigers and their situation with Jim Leyland is they do it on a year-by-year basis.
Normally, a manager on a one-year deal is considered a lame duck, who is doesn't command much respect in the clubhouse because the players figure he won't be there for the long term.
That wasn't an issue for Leyland last season working on a one-year deal. The players know and respect him. So they will do it again in 2013.
It's a good both sides. The Tigers aren't boxed in with Leyland in the long run, nor even the short term if it does wrong early next season. It's good for him because he can go somewhere else. He lives in Pittsburgh. It would not be surprising if at some point his managerial career goes full circle and concludes with the Pirates.
Some fans will be upset there were no coaching changes made after Gene Lamont's mistake of sending Prince Fielder home in Game 2 of the World Series. But with Leyland, like most veteran managers, you get his coaches. It's just part of the deal, and that is probably one of the reasons it is year-by-year deal.