Well, maybe I should change the name of this, as Alex Rodriguez had a decent post-season. Then again, i'm a stickler for tradition and a creature of habit.
This is a vague sort of Award. Choke/Disappointment has a broad range. And the winner (loser) this year is...
The offense of the Boston Red Sox.
The Sox scored 872 runs in the regular season, which was 3rd in the Majors. But they only put up 7 runs in their 3 post-season games. They feasted on bad pitching, but couldn't produce runs on demand. Their performance in the ALDS was a monumental choke.