Jonathan Obika's last-minute winner meant a fourth straight defeat for Leeds, who are now just five points above the bottom three and with a caretaker manager in charge.
Speaking in his first game since taking over from the departed Warnock, Redfearn said: "Whenever the manager leaves, it's upsetting - these are players that Neil Warnock signed. But they've applied themselves well.
"From a performance point of view, I thought we went a goal down against the run of play - we were doing well up to that point.
"I thought the performance and application was good, I thought we were unlucky at the finish because we should have got a couple of decisions.
"I thought it was a good performance without being spectacular, it was a poor surface. They will be disappointed, but they've been professional at what they've done."