Conor Townsend admitted Albion produced a performance far below their usual level at Molineux on Sunday lunchtime.
The Baggies were beaten 1-0 by Wolverhampton Wanderers in the Black Country derby, with Fer Lopez scoring the winner early in the second period.
James Morrison’s team struggled to get into the contest and rarely threatened the hosts’ goal.
Townsend, who played the entirety of the encounter, accepted Albion didn’t deserve anything.
The defender said: “It’s really disappointing. We know, as a team, we’re a lot better than what we showed on Sunday.
“Everyone is really disappointed that our worst performance of the season has come in this game.
“They are a good team, but Max O’Leary kept us in it. He was fantastic and it could have been three or four in the first half.
“It’s an error for the goal, but we can’t look to that. Max had kept us in it long before that and we didn’t deserve anything today. We have to dust ourselves down and go again.
“The lads were really up for it before the game. There was plenty of talk in the dressing room and it was all really positive. I actually thought we started pretty well for the first ten minutes or so, but then we seemed to come away from what we’ve been doing.
“It’s really disappointing to have not really threatened them at all. We’ve got to go away and work on that and make sure we rectify it.
“The dressing room was hurting after the game. It was the first Black Country derby for pretty much everyone apart from myself. It was despondent, but we need to dust ourselves off and get back on that training pitch and work hard.
“We’ve got a very young squad and our start to the season has been really positive, but we’re not the finished article and today showed that.
“We have to work hard, stick together and come back stronger after the international break.”
