It was a deliberate elbow from Vincelot in retaliation for shirt pulling & elbows from the Burnley player. It was shown clearly after the game. There were doubts about Barnes trying to jump over the player rather than stamping, but once seen, there weren't any doubts about the Frenchman.
The explanation as I understand it, is that he would have received a yellow card for the offence, if it had been seen at the time. He wouldn't have been sent off, therefore it isn't worthy of a ban.
We are so incensed because even though it was a yellow card offence, it should have been a free...