I think you guys are all missing the point. His voice hasn't changed he's just grown lazy, after performing stranuas songs every night hes just found the easiest way to sing them!
Look at the early performances of crawling for example? by the last chorus you can see hes in pain.lol
Also people have been saying about chester holding the scream on given up live? I don't recall this ever happening(with the exception of the Third encore session and the aol session) so if there is a live show can you point me in the direction cause it would be awesome to hear it?