What do you mean by his first season form, mate?
He played well in the first 4 games under Robson then was out a lot through injury and of course, Souness was now the 'manager.' Perhaps like some other players he could see Souness for the idiot that he is, especially after Ferguson. Unhappy players don't generally play to the best of their ability. Interesting that since he's returned he's looked a decent player again.
You won't like it as it doesn't fit your view, but replace Robson with Sounness, Sounness with Roeder and Butt with Parker and the argument contains some truths and half truths but overall is, well, still as incoherent as it currently is..