I read this on the MA forum as well. Supposedly he was always drunk on stage and screwing up songs, which I found hard to believe because the two times I saw Obituary (2009 and 2010) I was right in front of him and he nailed the solos both times.
8/29 - Sleep
9/13 - Samhain
9/20 - Overkill
9/23 - King Crimson
9/29 - Belphegor/Rotting Christ