Chris Basham acknowledged the Blades performance at Preston on Saturday had fallen short of the standards that have been set previously.
Speaking after the 1-0 loss at Deepdale, Basham remarked: "The manager wasn't happy and understandably so. We really wanted to step up to the plate, but it was another disappointing loss.
"We were disappointed for our excellent travelling support, we were upset with ourselves and worst of all we let the manager down, both collectively and individually."
United's number six added: "It's hard to say why we just fizzled out like we did. The first 25-30 minutes, we were well in the game and although we didn't create clear cut chances, we had opportunities.
"At half-time the manager wanted us to be dominant and we said to each we needed to start well, but unfortunately we didn't and before we knew it we were behind and chasing the game again.
"They came out, put pressure on us and took their big chance and after that we found it tough to break them down."