Better scream with deeper range than Carlile. Being a screamer is all about practice and repetition. It's probably going to take him awhile to get back into show shape, and he's gotta learn all new lyrics too that aren't his own. Give it time.
I don't care what anyone says, to scream a whole show is one of the hardest things to do. Jeremy Mckinnon can't do it, Shane Told can't do it...August Burns Red & Prada are two of the only bands I know who are able to do it well.