"The second half went wrong, we didn't turn up," BBC Sport quotes the Leeds manager as saying. "We didn't do the ugly stuff well enough in the second half so I'm very disappointed.
"It's the first time that's happened with me. I've been here many times and know what to expect and you've got to do it for 90 minutes, not 45.
"The second half came as a shock to my system. I'm bitterly disappointed with the players we've got, who are decent but are not at the level at this moment in time."
The result has left the club 15th in the Championship table.