More than 2,500 Baggies fans chanted 'sign him up' but Moore admits he has not even thought about it.

"You can understand why when he has scored a hat-trick today and he has put on another display," Moore said.

"He is a potent striker which his record shows and he illustrated why we want him at the football club and we are pleased to have him here.

"His energy, his enthusiasm for the game, his character, we are delighted to have him.

"He scores goals but he does tremendous work for the team and he is a joy to work with.

"We have not even spoken about it (signing him), we have got him here, we are just focusing on the short term, we are at the half way point of the season, there is still a lot of football to be played."

Gayle needed only six minutes to grab his first as he struck a free-kick under the wall, with Barnes making it two after 20 minutes when he fired home a rebound after Jay Rodriguez hit the post.

It was three on the brink of half-time when Gayle stabbed in and then his hat-trick was completed shortly after the restart when he capitalised on a poor error from Rotherham goalkeeper Marek Rodak.

The win ended the Millers' nine-game unbeaten run and Moore added: "This is a difficult place to come, we started on the front foot, we got the early goal.

"We didn't allow any real momentum, you can see why they have got a good home record. I was delighted with the boys and when it was on for us to play, they played."

It was the heaviest home defeat of Millers boss Paul Warne's reign, though he was left scratching his head at the severity of it.

Ryan Manning hit the post with the score at 1-0 and then later missed a penalty, also hitting the upright.

Warne said: "They are a very good side. They way we set up I thought is the best way to set up, the players' performances are as good as we could have asked for.

"The crucial moments in the game they took their chances and we didn't take ours.

"I don't think we could have played any better, we missed a penalty which summed up the day really.

"We were just on the side of unlucky, I don't think we deserved to lose 4-0 today but West Brom were the better team.

"We have lost 4-0 but I am not disappointed because the lads played as well as they possibly could.

"Another day we might have got the equalising goal when we hit the post. It wasn't like 4-0 and we took an absolute trouncing, we were always in the game.

"I don't feel shamed at losing at home to West Brom."

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