As Paul Pogba approached the interview area at Old Trafford only 15 minutes after Sunday's 1-0 defeat against Arsenal, you could see the frustration, the anger and the disappointment on his face. A little joke hardly made him smile. He was live on French TV, and he had a message to send through.

The most puzzling issue for him was maybe the contrast between the form Man United have showed in Europe -- dominating PSG (2-1) and RB Leipzig (5-0) in the last two weeks -- and their results in the Premier League, where they have won only twice (away at Brighton and at Newcastle) and are 15th in the table.

"It is so strange. I can't explain it. I wish I had the answer," he said.

The contrast between Man United's Premier League form and European form is also valid for the 27-year-old Frenchman himself. He was so good against Leipzig, giving a superb assist to Mason Greenwood, playing on the front foot in the diamond midfield set up by Ole Gunnar Solskjaer. He was on the left of that diamond, which has always been his best position.

Against Arsenal on Sunday, he was so disappointing. He lost the ball 15 times, won only four of 16 duels and had only one key pass. He could not get away from Thomas Partey's marking, rendering him unable to influence the game in a positive way.

Pogba knows he was not good. People who think he's happy with the situation are wrong; he came out publicly after the game precisely to show how much he cares.

The debate over Pogba -- his performances, his consistency, his future at Man United -- has been raging ever since he returned to Old Trafford in July 2016. He is, on pure talent, one of the best midfielders in the world. There is nothing he can't do. Yet it's been four years of ups and downs for him at the club level -- some will say more downs than ups, too. To get the best of him, you need a structure around him. You need to play with a plan, like United did against Leipzig and against PSG when he came on.

Against Arsenal, there was nothing. No movement, no tactics and no reaction, even after it became pretty clear how dominant the Gunners were in midfield. Pogba spent his second half on the left side of a three in the 4-2-3-1 formation Solskjaer played. Against Chelsea a week earlier, Pogba came on almost as a second striker, just behind Edinson Cavani. These are not his best positions. It's true that his talent should mean he can perform well regardless of where he plays. But in a team that's been quite dysfunctional at times and with no real collective strength, it is not easy.

Beyond his confusion around United's inconsistent form, he also took full responsibility for the defeat. He made "a big mistake" in giving away the decisive penalty when he was late to the ball against Hector Bellerin. You have to salute the fact that he acknowledged his error and spoke about it. He could easily have stayed in the dressing room and not said anything, but he is one of Manchester United's leaders and he wants to act like it. So he came out.

Pogba also expanded upon United's broader struggles at Old Trafford.

"Arsenal's plan was clearly to block Bruno and I. We should have found a way of dealing better with it. We should have found solutions so we could have more space. We knew it, but we could not impact the game like we wanted," he said. "This is not good enough. I have to do more, I know it. We have to as a team as well.

"We can't aim for the top when we don't win at home in the league."

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There is a fitness issue, too. To explain (or try to) his foul on Bellerin, Pogba told BBC Sport that he was out of breath and lacked clear thinking when he tried to get the ball before the Spaniard and failed. Let's not forget that he spent almost 10 months out last season due to injuries, that he had no real preseason and even that he tested positive for COVID-19 back in September and had to self-isolate for two weeks, forced to train on his own in his garden. Considering his size and his style of play, Pogba has to be at his best fitness-wise in order to play at his best.

Obviously questions over his future will inevitably return. He is under contract until June 2022 and right now, his future is the least of his worries. What he wants the most is to put things right on the pitch with Manchester United. The next two games, away at Istanbul Basaksehir in the Champions League and away to Everton in the Premier League, will be crucial to silencing his critics.