Tony Cascarino believes Arsenal played into Manchester United hands on Saturday by playing three at the back.

Arsenal have been using the 3-4-3 since last April and have had decent success with it.

Tony Cascarino, though, feels Arsenal are a poorer team when they use the formation, and the 3-1 defeat to Manchester United revealed why.

“Arsenal are a much poorer team with three at the back and it played into Manchester United’s hands on Saturday,” Cascarino said, as reported by the Daily Star. “If they have any aspirations to play in the Champions League, they have to play four at the back.

“What did United want? Space to run into on the counterattack. Arsenal gave Antonio Valencia that for his goal. With three at the back, you get dragged around, and space opens up when the full backs push forward.

LONDON, ENGLAND – DECEMBER 02: Arsene Wenger, Manager of Arsenal argues with referee Andre Marriner after during the Premier League match between Arsenal and Manchester United at Emirates Stadium on December 2, 2017 in London, England. (Photo by Laurence Griffiths/Getty Images)

“I do not believe the system suits Shkodran Mustafi, Laurent Koscielny and Nacho Monreal. It lulls you into a false sense of security, you indulge in wanting to play more, as Arsenal found out when Jesse Lingard caught out Mustafi before he scored.

“John Stones had that problem when he played in a three at the back. If Mustafi had been in a four, he would be giving the ball quicker.”

The idea that it was the formation that cost Arsenal is a silly one, given the number of times the Gunners have won while playing three at the back. It was individual errors which cost them on Saturday, in my opinion.

It wouldn’t have mattered how many players Arsenal had at the back. If you give the ball away in your own defensive third, opposition sides will create chances to score against you.

It’s not three at the back that encourages Arsenal to play more. They would have done exactly the same with two centre-backs or even one, I feel.

Mesut Ozil for Arsenal against Manchester United.

The system apparently doesn’t suit Shkodran Mustafi, Laurent Koscielny and Nacho Monreal despite the three not conceding a goal together this season until Saturday.

It’s amazing how quickly one result can alter people’s views. Nobody was questioning the shape when Arsenal used it and defeated Tottenham just a couple of weeks ago.

Players make errors no matter what shape they’re playing. That’s the real issue here.