Bristol Rovers boss Mark McGhee was at a loss to explain his side's poor showing in the 1-0 defeat to Port Vale.
Marc Richards' 16th goal of the season secured the points for Vale before Rovers' Tom Parkes was shown a straight red for a high tackle on Chris Shuker.
"It's been a disappointing day all round because we didn't play well at all," said McGhee.
"I thought it was an even game until Vale scored the goal, but after that we never looked like doing anything. We were poor in possession, our passing was poor and for some reason the players seemed to lack energy.
"We were nowhere near as bright as we've been in most of our recent games and I don't think we would have got anything with 11 men.
"Sometimes it's difficult to explain when teams don't perform, but it does happen to everyone on occasions."