Clutch will always be extremely difficult to measure for hitters. Even if they are clutch they still fail most of the time. The advantage always lies with the pitcher and the defense.
According to Fangraphs 13 mill should get you 1.8 WAR or something like that. But whatever...if he keeps pitching like this the rest of the way he'll have earned his money, and he'll be back next year for another ride.
I believe that for a lot of owners it's not just all about the money. The money is crucial but the biggest rush of all is holding that championship trophy. I think Henry is one of those owners. Otherwise he might have cashed out already in one of those periods when things have been sour.