United were downed 2-1 by Sevilla, who stunned their hosts with two goals in four second-half minutes.
Pogba had entered the field for Marouane Fellaini on 60 minutes but failed to change the game.
Sub Wissam Ben Yidder himself came on an two minutes later scored for the Spaniards.
And former Scotland striker McCoist has called out £89m signing Pogba for his role in the defeat.
“I’m not sure about Paul Pogba,” he told BBC 5 Live.
“If that’s me coming off the bench I’m going to try and show how I can win the game.
“He looked lethargic when he came on and was poor tonight.
“On tonight’s performance I think you would struggle to find a more overrated player.
“I would question his attitude to go and make an impact in a Manchester United jersey.”