I'd top out between $36/3 years and $30/2.
I'll let Steven Goldman explain why:
Rivera threw approximately 5% of the team's innings in 2007. Even though the Yankees used him in many crucial situations that magnified the importance of those 71 innings, the fact is that his opportunities are limited.
Now, it could be that this delay has something to do with Mo being in Panama and out of touch with the front office.
But I doubt it.
Mo was clearly pissed about not being extended in the spring, and he was pissed again when Torre was fired.
Other teams endure a lot of agita from their closers, and Yankee fans having been getting more of that every spring. I'm pretty sure Mariano is not worth 33% more than any other reliever in baseball. And that's before we include the luxury tax.