Danny Wilson was left to rue defensive errors as the Blades slipped to a shock 3-2 home defeat against rock bottom Hartlepool United on Saturday.
A double from veteran Steve Howard and a strike from Unitedite Ritchie Humphreys paved the way for an away win and despite a first half goal from skipper Michael Doyle and a consolation deep in stoppage time from Harry Maguire, United saw their unbeaten home record shattered in the final game of 2012.
Looking back on a frustrating afternoon at a boggy Bramall Lane, the Gaffer commented:
"I am surprised and dissapointed, of course I am. It is only a few days ago since we were absolutely fantastic against Scunthorpe, but today (Saturday) we were quite the opposite.
"You have to give credit to Hartlepool, they came here and worked they tails off. They got the breaks at the right times but that was mainly down to our poor defending.
"Hartlepool played a direct style up to big Stevie (Howard) and we struggled to combat that threat, but it was especially disappointing we didn't get hold of the second ball more often.
"Our final ball from good areas wasn't good enough and again that was particularly frustrating.
"We weren't at the races but now we have a few more days to put things right before the trip to Doncaster (Rovers).
"We will be criticised because of where Hartlepool are in the league, but I have said many times before the bottom teams are capable of beating the top ones, this proves it."
Key decisions, including a disallowed goal which would have made the score 2-1 in United's favour early in the second period, went against the hosts, but Wilson refused to blame poor decisions or the testing conditions for the defeat that saw his team slip to second in League One entering 2013.
He concluded: "We started both halves very well before conceding sloppy goals, we were on the end of a couple of shocking decisions, especially when Andy Monkhouse hacked down Harry (Maguire) and what compounded that situation is Harry got booked in the melee that followed.
"Ryan's goal wasn't offside and would have put a totally different complexion on the game, but we have to look at ourselves in other areas to why we lost the game.
"Everyone was desperate to get the match on, it was a heavy pitch but that is no excuse because it isn't going to be perfect conditions at the end of December.
"The conditions didn't make us concede three goals, it was simply poor defending. It did affect us going forward, but we should have adapted better and we didn't"