Pogba has shone since Ole Gunnar Solskjaer replaced Jose Mourinho as manager in December, though the Frenchman’s performances have dropped off again in recent weeks.
Pogba struggled under Mourinho, despite playing a pivotal role as France won the World Cup last summer.
Manchester United paid £89million to bring the midfielder back to Old Trafford from Juventus in 2016.
And though Phelan, who returned to United alongside Solskjaer, knows he has the ability, he also believes Pogba hasn’t reached his full potential despite improvements after a difficult spell under Solskjaer.
“I think that happened to quite a few players, they probably drew into themselves a little bit and were very cautious,” says Phelan.
“Paul had a spell where all the eyes were on him and delivery of his best wasn’t there all the time, the consistency.
“Now we are trying to apply ourselves to Paul’s game.
“Ole has done a terrific job at helping Paul through certain spells and he has embraced that. He is maturing all the time.
“He is not the finished deal even though everyone looks at him and sees a World Cup winner already but he is not the finished deal, there is still a lot more to come and that is the exciting bit about United.
“There are players there who haven’t achieved for the club what they need to achieve and we want to make sure that they relish that experience, embrace the opportunity to win things at Manchester United.”
Pogba’s United future is seemingly always up in the air with it recently reported that Real Madrid are interested in the Frenchman.
And it has been claimed that the La Liga giants want Pogba to tell United of his intentions to leave Old Trafford before they pursue a transfer.
Ok Diario say Real want Pogba to put pressure on his current side to let him go and then they will swoop.
Manchester United welcome Barcelona to Old Trafford on Wednesday in the first leg of their Champions League quarter-final tie.