To add to their misery defender Leon Barnett limped off after Mowbray had used all three substitutes leaving Albion to play out the game with just nine men.
"Luke's sending-off did affect us. It looked like he went chasing a ball," the Baggies boss said after the 4-1 defeat at The Hawthorns.
"Officials make decisions that they see and we have to abide by them.
"Luke was very quiet after the game and we will have a chat with him when things calm down. He is a young player who is trying to impress.
"We have just got to get on with things now and we won't look too deeply at today. We need to move on to the next game.
"We got our noses in front and who knows what would have happened if it had stayed eleven v eleven. I think it could have been different.
"We know that have got to win some games now."