Brandon Thomas-Asante and Grady Diangana subbed due to knocks – West Brom boss Steve Bruce

The double change 10 minutes from time in the stalemate with the Hatters drew a vocal and angry response from home supporters at The Hawthorns.

Striker Thomas-Asante and left winger Diangana had been Albion's livelier attackers as the Baggies struggled to break down Luton and their numbers being shown led to a chorus of chants and boos against the manager and club's board.

Bruce, though, revealed Diangana had sustained a head injury and was seen by club's doctor while Thomas-Asante was also struggling with a knock.

The manager revealed: "I think that's why supporters stayed with them.

"To the supporters – Grady's got a knock where he's seeing the doctor, I didn't think he had any energy left in the second half.

"The same too goes with Brandon, he's carrying a knock.

"But no doubt Brandon being Brandon – and I'm delighted he's the cult hero by the way, I'm delighted I brought him to the club and they associate with him.

"They see in him being raw and aggressive in his work, he plays with his heart on his sleeve. He's done great the kid."

The manager argued the introduction of John Swift, a prolific creator for former club Reading last season, and 18-goal Karlan Grant, was what he felt could help with 10 minutes left.

Swift was dropped from the league XI for the first time this season while Grant returned to the bench following a subdued display at Preston in midweek.

He added: "However with 10 or 12 minutes to go I'm bringing on a player, well two players, one's got more assists than anybody else in the division and Karlan Grant scored 18 goals for us last year. It's not as though I'm bringing on two central defenders.

"I understand the frustration, they want to see their team win.

"As I reiterate to you the pair of them have got knocks, Grady in particular is not in a good place with the whack to his head, we're mindful of that.

"But I understand the frustration totally."