Well, they did have a poor spell after that rant, during which we created a gap that served us well when we slipped up against Liverpool and Fulham. It certainly got a bit hairy with that Villa game (Macheda) and when we went 0-2 down against Spurs because by then Liverpool were winning almost every match, which they did until the end of the season (except the 4-4 against Arsenal).
I doubt the rant in itself had much to do with it. It's what it may have symbolized - Benitez took his eye off the ball and focused on nonsense. Maybe it cost his team.
He was a very good coach, he did brilliantly with Valencia and did a good job with Liverpool. But his final year there ruined everything, for them and himself. He spent money badly and by the time he left, I doubt the squad was much better than when he inherited it from Houllier. His image isn't always fair because he was better than some give him credit, but he seems to have lost something.