Pogba has found himself on the bench in recent weeks, with manager Jose Mourinho becoming increasingly exasperated with the player’s form.
That followed a much-publicised falling out with Mourinho earlier in the season, resulting in the 25-year-old being stripped of the vice-captaincy.
Mourinho even went as far to say that Pogba would never wear the captain’s armband again while he remained in charge at Old Trafford.
That has inevitably led to almost daily speculation about the midfielder’s future, with some reports suggesting he could move on as early as next month.
Keane admits he is an admirer of Pogba’s abilities but the former Red Devils skipper launched a withering attack on the player’s attitude, questioning his commitment to the club.
“I would [play Pogba], he's clearly a talented player. Whatever's going on his head... he seems to be letting the manager down,” Keane, speaking ahead of United's game at Liverpool on Sunday, told Sky Sports .
“The manager's brought him to the club, made him captain earlier in the season. Now we don't see what Pogba's like on the training pitch or when they're travelling to matches, but if the guy's not pulling his weight it doesn't matter who you are, he deserves to be left out.
“So, I think Mourinho has got to be brave on that side of it, which he is. We go back to characters – if you play for a big club like Manchester United or Liverpool and you're not in great form then you roll your sleeves up and you become a really good team player.
“[Making him captain] might be Mourinho trying to get him onside – people say he doesn't do enough to get players onside, but maybe that was a nice touch to say 'listen, there's obviously something amiss here, I'm going to make you captain' and obviously Pogba's thrown it back in his face.
“He's obviously done something to really upset him and it must have been really bad because when he's taken it back off him he's probably lost the player there with that decision.”