Speaking after the 5-1 defeat, Flitcroft said, "First half - I was okay with the performance.
"We tried to contain them and to try and build some confidence. First half, I think we got that.
"I think second half at 2-1, I felt and believed we could get to two-all but when that didn't happen we gave them the ball to easily.
"We defended really poor all over the pitch.
"I'm really disappointed with the aspect of how we defended as a team.
"We thought we could snatch a goal and get the game back to two-all. But I'm disappointed with how the lads reacted to goals.
"First half we conceded one goal and I was okay with it. Second half they opened us up too easily.
"It's sink or swim time. Tomorrow morning I better have a group of players who better fight."
Mike Pollitt made his Barnsley debut having only just signed a 28-day loan earlier today.
"I've felt for quite a while Luke Steele was not under enough competition," he added. "I felt I could relieve a bit of pressure on Luke.
"Luke's been rested tonight, and it was a good opportunity to try something different."
