As with most complaints, its the inconsistency of the decisions. For example, VLP catches their player and free kick is given. 2 minutes later VLP is chopped in half with a dangerous challenge and nothing is given at all and then VLP goes shoulder to shoulder and a free kick is given. It appeared at times that slight niggly challenges resulted in a free kick for Blackburn but we needed to be all out assaulted to get something. He also didn't keep up with play. Towards the end of the game, Doherty was hacked down but the ref was nowhere near the incident and missed it and tried to make out the ball had been won (it hadn't btw)
He did get one great decision when he booked a Blackburn player for diving. That said, he should have had a word with David Dunn who play acted like a right cunt. Got clipped, went down, rolled around in agony holding his ankle, ref waved play on, he looked up, got up and carried on his wobble towards the penalty area. (that's more of a complaint at Dunn but I wish the refs would slap that behaviour down)