Wahbi Khazri was taken off in Sunderland's latest match against Norwich City.
Although the Black Cats managed to pick up a 3-0 win at Carrow Road, Allardyce opted to replace Khazri with Duncan Watmore at half-time.
Khazri had failed to get particularly involved in the first half of the contest, and Watmore’s introduction clearly had a positive impact on the team.
The 22-year-old looked very lively throughout, and he scored his side’s third goal in the contest.
Watmore’s performance impressed Allardyce, but the Black Cats’ boss was less pleased with Khazri’s display.
“Khazri was not functioning as well as he has done,” he said. “We had the Roadrunner (Watmore) back, and we needed his energy and ability.
“You could see what trouble he caused Norwich and I’m so glad he scored because he had so many chances or to make the right pass to Jermain (Defoe).
“It was a great finish in the end – cool, composed, around the keeper and in the net.
“Wahbi didn’t quite get to the level we know he can. We had people on the bench who came on and did a little better.”
Khazri’s display at Carrow Road was arguably his most disappointing in a Sunderland shirt to date.
The winger has been a revelation since moving to the Stadium of Light in the January transfer window, and he has added a great deal of creativity to their attack.
Sunderland’s win over Norwich has lifted them to within one point of safety, with their next match coming against Arsenal on Sunday.