Men, if you didn't already hate Chris Evans for his incredible physique and spot-on performance as the Human Torch in "Fantastic Four",
see how he looks in "Captain America", which requires him to be a little bigger.
Well, he
is bigger, but still looks limber enough to mix it up the way Captain America does.
Is it a big role? Sure. "Thor" can be a flop and it won't impact "The Avengers" movie, just like "Hulk", but without a good Cap, there is little chance "Avengers" can work.