I think that the first opt out I ever heard of was Arod's option in the Rangers deal that was traded to the Yankees. He, of course, had an MVP season and opted out of the richest contract in baseball history. The Yankees proceeded to bid against themselves to give him a new richest contract in baseball history. The results are ours until the close of the 2017 season.
Since then, the opt out has become a more and more common tool. CC Sabathia got one, and the threat of it turned into a one year, $30M extension on his existing deal. Zach Greinke got one from the Dodgers, as did Clayton Kershaw.
And now the Yankees have given one to Masahiro Tanaka.
This is, perhaps, the worst concession in a deal the Yankees had to make.
Look, without Tanaka replacing Andy Pettitte, the Yankees look to me like an 85-win team. They are better than they were last year, but they played so far above their heads last year that they needed to improve the lineup in order to fight for third place in the AL East. With Tanaka, I think the Yankees have a shot at 90-93 wins; that's the wild card sweet spot.
But what it means for the Yankees is that if Tanaka is terrible, they're stuck for more than $22M per year until 2020. And if he's just ok, $22M until 2020. And if he's above average, $22M until 2020. And if he gets hurt, $22M until 2020.
But if Tanaka is great... If he's Yu Darvish... If he's an ace... If Tanaka is great, then he'll opt out at age 29. And he'll get a Clayton Kershaw deal that carries him into his late thirties.
So the Yankees have taken on 7 years and $155M worth of risk, and the upside is only 4 years of reward. It's a great deal for Tanaka. The Yankees are better off with him than without him. But, was at best, a necessary move. Certainly not a great deal for the Yankees.