Although Pogba has missed much of the campaign through injury, the Frenchman has been used in a number of different central roles during his time at Old Trafford.
However, having endured a mixed period since his return to the club in 2016, Van Persie wants the club-record addition to speak with Ole Gunnar Solskjaer regarding his position going forward.
The Dutchman told Stats Perform: "It's very difficult. With Pogba, it's an interesting situation. Pogba, in my opinion, is a world-class player, he has proven it over the years. He has it all.
"But first, I think with him, and that's after a couple of years now, I think he should come out and he should say what his favourite position is. If that's done, then people can judge him based on this position. Now, I don't think people really know if he's a six, if he's a number 10, that's a big difference.
"I have the feeling people judge him a bit unfairly. They expect 20 goals, they expect 20 assists, they expect Pogba to make Manchester United champions. But, is he a six? If he's a six, then you cannot expect 20 goals. If he's a 10, maybe 12 to 15 goals. So, it's not really fair on him because it's not really clear."
The World Cup winner has contributed 31 goals from 143 appearances for United in all competitions.