Upset with his successor agreeing with Damien Duff's assertion that his high-tech fitness methods failed to work, Big Sam said: "There was nothing wrong with the match fitness when I was there, so I think that's a little bit of an excuse.
"Sometimes fitness is a mental thing and I think mental fatigue can hit the players more than anything.
"That's when it looks like they're not trying or running as much as they possibly can do because of the fear factor and that can drain an awful lot out of the players.
"That may be the problem at the moment. I think it can boil down to that - not a lack of match fitness.
"They must get a result pretty soon. They've got Birmingham and Fulham in the next few games.
"They could be the big games, the turning point for Kevin."