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Manchester United's 4-0 loss to MK Dons on Tuesday night sent Twitter, Facebook and every other social media platform into complete and utter overdrive, with fans of the club despairing and rival supporters savouring every moment of the collapse.

Losing by such a margin to a League One side is unforgivable, no matter the changes to the XI, but how exactly did it go so wrong?

The Red Devils started the game with Javier Hernandez, Danny Welbeck, Jonny Evans, David De Gea, Anderson and Shinji Kagawa. Adnan Januzaj was brought on later for the Japanese midfielder, too.

It's a strong side, and it should play better; to finish goalless against a League One side with these players in the team has furrowed many a brow. How much is the 3-4-1-2 system, persevered by Louis van Gaal, to blame for the disconnect in the side?

Struggling with the System

United fans were on cloud nine after securing the British record transfer of Angel Di Maria from Real Madrid just hours before the match, but by 10 p.m. BST, they were perhaps hoping the Argentine had missed the dismal outing at stadiummk.

This felt like a clear and obvious banana skin, and rather than relieving pressure on the side by changing the XI dramatically, Van Gaal actually piled more on by sending out an unfamiliar set in front of 26,969 raucous fans, per The Guardian.

Forget everything you saw in pre-season. Many, including this writer, can be guilty of taking too much from such limited stock, and the same can perhaps be said of Arsenal's mercurial defeat of Manchester City in the Community Shield.

If there's one thing guaranteed in pre-season, it's space. Remember Ashley Young buccaneering forward against Real Madrid and putting them to the sword? Against Sunderland, he shied away from penetrative runs, instead passing inside and failing to maintain width.

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With more space, passes and runs are easier. MK Dons didn't give United a moment of peace on the ball, and that bore fruits when it came to interceptions, forcing errors and picking up stray balls.

The main issue players struggle with in a new system is basic passing options. Barcelona players grow up playing 4-3-3 and, as a result, largely know where their colleagues are at all times without having to look. They have a picture of the pitch in their own heads.

For instance, the defensive midfielder will have clear "Pass 1, Pass 2 and Pass 3" options in his mind—the passes he knows are his go-to's when constructing a move or evading danger. Those are set in stone as long as the formation doesn't change or your colleagues don't let you down.

Your Pass 1, Pass 2 and Pass 3 change when the system changes. A 3-4-1-2 is drastically different from a 4-3-3.

Example 1

Take this example of Michael Keane on the ball:

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He's just been passed to by Anderson, and now he's looking up to find a pass himself. In a more regular, back-four-based formation, there would be a player in each of the highlighted sections of the pitch. In this formation, there isn't, but there needs to be a player entering the space to offer the pass.

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No one does. He takes an extra touch. MK Dons' three markers get even tighter to their men, and Keane ends up trying to force a pass into the forward zone highlighted. It's intercepted, and the Dons push on into United's half.

Keane expects a player in the No. 8 space and in the No. 10 space, but neither is present. It forces him to re-register his passing options—something he's not used to doing—and he loses the ball.

Example 2

Seconds later, Anderson wins the ball back and puts Nick Powell in possession. He edges forward, looks up and is finally forced to punt a long ball to Welbeck on the left—despite the No. 10 and No. 8 spaces being wide open again.

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The ball goes out, as it's overhit, and MK Dons are back in possession. Welbeck swats the air in frustration, but why wasn't he—or, more importantly, Andreas Pereira—breaking his neck to enter the highlighted space?

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Powell had time to pick them out, perhaps rushed his pass but saw no one entering the right areas.

Comparisons

The issues are not too dissimilar from the ones the first team are facing, nor are they that different from the issues the Netherlands struggled with during the FIFA World Cup.

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In the first two Premier League games, Juan Mata has struggled to get free of his markers and dictate. He isn't receiving passes in the right areas, and considering the amount of possession United have averaged over the first two games (57.3 percent, per WhoScored.com), he's not receiving enough passes either.

The Dutch struggled mightily to work the ball through midfield during the World Cup because Wesley Sneijder failed to shake the attention on him, forcing long balls from back to front.

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They got away with it because Arjen Robben is superb; Manchester United haven't been so lucky.

Many took a sharp intake of breath when Van Gaal confirmed he would continue with the 3-4-1-2 for the Premier League season, as no manager had ever won the league with it before.

His mettle will be tested to the extreme after a third poor result in a row, as it's obvious none of his players are adapting to the new regime quickly enough.

We've focused on United's attacking issues here, as the defensive ones are obvious. All four goals were caused by individual errors in possession, which is in part caused by systematic changes (passing options again) but also the player.

Jonny Evans should not have played the pass for the opener in any formation, and he should have been a yard or two tighter to the crosser for the second goal.

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