This is how it's done

No? I don't think so

He was only like this for a bit so they probably didn't put too much care into how it looked

I mean he was supposed to look weak and skinny and weird and awkward right?

True but I mean more in a it looks poorly done not he looks awkward way? Am I making sense?

They were going to have a completely new actor and I think that would have ruined it more than a little bit of crappy green screen. I'd rather Chris Evans looked a little bit off for the first half hour of the film than they bailed on it.