Chris Wilder watched Oxford fall to a fifth straight loss at home to Bradford and admitted his side had lost their confidence.
Goals from Andrew Davies and Nahki Wells inflicted the club's worst run since Wilder took charge four years ago, with the U's managing just one shot shot on target in the 2-0 defeat on Saturday.
"Everyone can see we're not playing with any sort of confidence," Wilder said. "In the first half we did okay but we gave ourselves a mountain to climb when we went behind. To concede two goals from set-pieces is really poor from our point of view.
"I think the majority of people see it the same as I do, that we're very low on confidence. When the second goal went in there was a flatness about us then.
"I've got to possibly change our tactics and change the system to turn things around and get a result. But I say 'please judge us when I've got everybody back'. We've got eight or nine out and some of them are big players for us."
"We bought players into the football club to play through teams, we don't play back to front and smash it like some teams, but I will possibly look to have to change the tactics through this difficult period. Maybe change it to go and get a result."