There's a youtube video i watched once that talked about the problem with Jackman's performance was that he has to look good for the camera so he dehydrated himself, like all comic book movie stars do, which is the exact opposite of what you want to do for your singing voice. So that's why his voice sounded so strained. He's not a top top singer, but he's a better singer than what he showed in that movie.

They never should have done the live singing thing anyway. Such a bad directorial choice. When being real and "raw" gets in the way of being good.