I'm sure we watched the incident about a million times at the time all you can tell is that both of Hayes feet slip out from under him as he's coming forward before any punch is thrown. As he is falling to the canvas Barrett throws a punch which may have either grazed the top of Hayes head or missed high, the video is inconclusive. The punch didn't cause the 'knockdown'. The referee called it a slip.
I stand to be corrected but I remember it as Haye getting clipped, going down for a non-too-serious looking KD and getting another one for good luck while he was on a knee. EDIT: Didn't see Cobblers post.....guess its a tricky one to call.
Haye slipped to one knee then Barret hit him. So no it isn't a knock down. And that's why it wasn't given.
That's a fairly ugly mix of stupidity and self righteousness you've got going on there. Read the thread. It's pretty plain to see we're not talking about the shot when Haye was down. It's the shot that hit him at the same time as he slipped. 4:40 here (not a great angle or speed to view it though) http://www.youtube.com/watch?v=rtvGY3F_JmM I recall seeing a replay that showed quite clearly that left hand clipped him even though he had slipped moments before.