Hopkins

When an actor's performance in the trailer doesn't sell their performance but upon seeing the film, it's clear that it is actually a genius performance.  

Origin:  Anthony Hopkins was totally unbelievable as Richard Nixon in the trailer, but when Pete saw the film, he realized he'd been wrong and that Hopkins was genius.  

Usage:  Hugh Jackman looked ridiculous in the trailers for Real Steel but, man -- watch the movie.  He really pulled a Hopkins.  He's great.

First Used:  28 Days Later