Barnsley
The Baggies briefly rallied with James Morrison pulling a goal back in the 58th minute however the travelling support of 3,971 were left disappointed as
"A poor 90 minutes ruined the day," Mowbray said after the defeat.
"There were a lot of below-par performances.
"We got what we deserved from the day.
"Let's give
"But we had too many players off form today and well below the standards they have set themselves each week.
"We could have been a goal down inside two minutes and it was an unacceptable first-half performance.
"I made two changes at half-time but, let's be honest, I could have made a lot more.
"There was a lack of quality from us today, which is unlike us.
"We didn't have enough to ultimately get back in the game and take something from it.
"It was a shame for the fans.
"We brought a great following and we didn't repay their support."
Mowbray's men now have the perfect opportunity to amend the Barnsley defeat with Sheffield United and former manager Bryan Robson visiting The Hawthorns on Tuesday with the
"The players are aware that I'm looking for a reaction," Mowbray continued.
"We've had a very good season so far and we occasionally slip below the standards we have set ourselves.
"The task now is to get back to where we know we can be and, when we're at our best, I would suggest there is nobody better.
"If you fall behind the standards you set anyone can beat you in this league."