When Juventus clinched their fifth straight Serie A title in April, they celebrated at the training ground, with Paul Pogba dancing on a table.

The Scudetto was sealed not while they were on the pitch, but by a Roma win over Napoli, meaning the Old Lady of Italian football could, once again, not be caught.

But the hard work had been done, by Pogba and Co, the previous day - as well as in the previous months - when they beat Fiorentina away from home.

Paul Pogba gesticulates angrily during Manchester United's defeat by Watford on Sunday

Pogba struggled in a midfield alongside Wayne Rooney (right) and Marouane Fellaini (left)

The midfielder flourished on the left of a midfield three for Juventus, but is in a new role now

That day Pogba lined up, as he tended to do at Juve, as part of a midfield three, alongside Sami Khedira and Mario Lemina.

Two months earlier, in another huge fixture, Pogba started on the left of a midfield four against Bayern Munich, this time alongside Khedira and Claudio Marchisio.

At home they earned a creditable 2-2 draw, and then away, this time with Hernanes in place of Marchisio, they raced into a two-goal lead, only to be knocked out in extra time having led going into the final seconds.

On all three occasions Pogba was the dominant player for his club, influencing the game, earning plaudits and establishing both himself and Juventus at Europe's top table.

On all three occasions, and indeed throughout his time at Juve, Pogba played, largely, on the left hand side. He was sometimes used in a three, sometimes in a four, but always influencing the game from the left.

Pogba did have one excellent effort that rattled the crossbar from 35 yards in the first half

With Rooney in the side Pogba is asked to do more defensive work than he is comfortable with

The Manchester United captain has been short of his best this season, playing as a No 10

He was never a winger. But his defensive contributions were limited by the presence of two 'proper' central midfielders, who could control the tempo of the game and protect the back four.

Contrast that to Pogba on Sunday, when his Manchester United side were not only beaten, but beaten comprehensively by Watford.

The Frenchman was nominally at the base of a 4-2-3-1 formation alongside Marouane Fellaini, while Wayne Rooney filled the most attacking midfield role.

Pogba shouldn't take too much blame for the defeat - he wasn't brilliant, but several of his team-mates were worse. He didn't give the ball away, as Anthony Martial did, for the first goal. He was in a decent position for the second, but could not quite intercept the cut-back towards Juan Camilo Zuniga. And he had perhaps United's best effort on goal, with a brutal drive which hit the bar in the first half.

But he wasn't at, and is still yet to produce, the level of performance of which we know he is capable. And it is quite possible that a large part of that could be down to his position at United.

Whereas at Juventus he always had two 'proper' midfielders alongside him, at United he has been shoehorned into a midfield three in which he is the central member.

Pogba's pass map for the game against Watford, with just one successful pass into the box

Rooney created only one chance from open play, and drifted all over in his midfield role

United's average positions - Fellaini (27) was left isolated as both Pogba (6) and Rooney (10) wanted to be the most attacking midfielder (the positions of Anthony Martial, 11, and Marcus Rashford, 19, are distorted, as they both played wide but swapped wings throughout)

On Sunday he had Fellaini behind him, and Rooney in front. It might look good on paper, but in reality it was a recipe for disaster.

Take the first goal. When Martial has the ball, Pogba sets off down the left touchline to start a counter attack - precisely the kind of proactive move you can make if you are the foremost of a midfield three, or the left midfielder as part of a four.

But when Martial lost the ball - or, as Jose Mourinho would have it, was fouled - United were left with two of their midfield three, and their left back, miles ahead of the ball.

In swept Etienne Capoue, with Rooney 10 yards behind him, to put Watford ahead. Watford's central midfielder had space in the United box, as two of United's midfield trio roamed upfield.

Defensively, then, Pogba as part of a midfield two leaves United exposed, but that would matter less if going forward he and Rooney were able to create chances.

But the reality is that they aren't doing so. Pogba has yet to provide a goal or an assist this season. Rooney has managed two assists and one goal. Uninspiring stuff.

On Sunday Rooney created one chance from open play, Pogba none. They managed a combined two successful passes into the Watford box. Neither had a shot on target. Pogba barely managed a successful pass into the final third, while Rooney's involvement was peripheral at best.

The shot maps of Pogba (left) and Rooney - they didn't manage a shot on target between them

Rooney was a peripheral figure in the game, failing to create chances to dictate the play

Both have had plenty of criticism this season, and the truth is that neither have been quite as bad as some pundits would like you to believe.

But both like to drift around the midfield, both need to be the most advanced player in a three - if Mourinho is determined to stick with the same formation - with two others doing the more responsible work to win the ball and dictate the play.

For now, it is Pogba who will get the more negative attention. He cost £100m, and is yet to show even a hint of producing play worth that much.

But Rooney has been poor too, and at 30, seven years older than his team-mate, he may be the man to miss out if Mourinho does adjust his system.