Originally Posted by Drizzle
While I originally wanted Giacchino to score The Avengers, I was very satisfied with what Silvestri gave us. I'm sure Giacchino would have given us something similar.
Especially considering Joss probably had something in mind for the score and conveyed that to Silvestri, which is what got put in the movie. If Joss hadn't liked the score at all or didn't feel it fit with what he was trying to convey on-screen, then he would have had it changed.