"There was not enough determination, desire or drive in our performance," Megson said after the 1-0 defeat at The Hawthorns.
"When you haven't got that you won't get where you want to be.
"Our efforts to defend when they got their goal were poor, we just didn't deal with it. It's soul-destroying because we have been working hard in training to try and put these things right."
"United were well organised, they worked hard and they made life difficult for us apart from the first 20 minutes.
"It's very frustrating because we had the chance to go level on points with Norwich at the top of the table.
"My players have got to show a lot more drive at that point. You don't hope you can go up - you have got to really want it and to push for it. We didn't have enough of that.
"This was a bad day at the office. I made three changes to the team after the break but we quickly went back to the same malaise we had been suffering from early on."