Me and the Mrs were at that game. When we came out, a line of young coppers were keeping the supporters "apart". The Port Vale fans were sort of bouncing up and down on the spot and shouting "come on then!", and Blades fans probably doing the same. One Port Vale fan came running up, towards the line of coppers, with an empty plastic water bottle in his hand, he threw it, it went about a foot forward and then the wind picked it up and blew it about 10 feet back, into the Vale fans (not gonna get hurt by an empty plastic bottle anyway!).
I had parked in the home supporters car park (because we arrived late, and didn't have time to drive around), so I walked up to the line of coppers and asked to be let through. Young police woman said "sorry, it's not safe", I said "but my car is parked over there", pointing at the car park, a young male copper said "might be best if you hang on a bit". I looked at the Vale fans, most of which (the noisy ones), looked like they would soil their boxers if you popped a balloon behind them, and said to the copper, "don't think they are going to do anything really, do you?, we need to get back home", he looked at me, looked at them, and said, "off you go", and they un-linked arms, and we walked through, it went quiet, the Vale fans parted, making a path for us to walk through, and a few minutes later, they all swarmed together again, bouncing up and down and shouting "come on then!" to the other Blades.
We just walked through them, not one said anything. If our "lads" are like that, it's all for show and most of them would not know what to do in a real fight.