Chris Wilder was visibly frustrated in the aftermath of Saturday's loss at Birmingham City.
United left the Midlands empty handed, despite Mark Duffy's early opener on his return to St Andrew's.
And Wilder wasn't impressed with what he witnessed against the Blues.
He remarked: "We're always trying to get better and you do have days in this division where the opposition might be better than you.
"But I didn't enjoy watching us, we looked tired and leggy, we didn't win first balls, we didn't react to second balls and we didn't make good decisions.
"The players knew they'd press us and be on top of us. We picked Clayton and Duffy for a reason and it was a blow that Leon wasn't available.
"There was grass in behind and we got off to the perfect start, they come back into the game, but we should have beat their press by going over the top."
The Blades boss added: "Their first goal is a gift. We had great possession on the left, too many touches sees us concede a corner and then two people then don't do what is asked of them and the whole place lifted.
"They were nervous and we should have built on the pressure having scored early. We made into a 50/50 game with our decision making and that doesn't suit us at all.
"We didn't threaten enough in the final third, they did, they made better decisions than us and scored a simple second really, with a ball in behind our defence."