Why Arsenal and Wenger must stick to three at the back for their FA Cup semi-final

Arsene Wenger is not a manager who’s particularly prone to tactical tinkering. When he set his team out in a 3-4-3 system at Middlesbrough earlier this week, it was the first major formation change in eight years—and the first time he had deployed a back three since 1997. The switch was relatively successful, enabling Arsenal to record a rare victory away from home. Having made the transition, Arsenal and Wenger must now stick with it—starting with the FA Cup semi-final against Manchester City.

In some respects, moving to a back three felt like a last throw of the dice from a manager who had looked distressingly unable to arrest the downwards trajectory of his team. It’s been a highly popular formation this season, notably at Chelsea, but Wenger is famously loathe to go with what he perceives as ‘trends’, preferring, where possible, to stick with his intransigent vision of football.

However, to an extent his hand was forced: Speaking to arsenal.com after the game, Wenger effectively admitted that he felt he had no choice but to make a change to reinvigorate his troops:

“Sometimes when a team lacks confidence, just to add something new to believe helps to focus and overall the fact that we conceded three at West Brom, three at Crystal Palace, I felt it was needed.”

It feels like a tacit admission that the players had lost faith in Wenger’s previous tactical plans, and a fresh approach enabled them to play with a measure of conviction once again.

However, there were also genuine strategic benefits. Very simply, fielding three centre-halves gave Arsenal more cover in the middle. The Gunners have struggled to provide adequate protection for their central defenders all season long, and perhaps Sam Allardyce’s post-game boast after the Crystal Palace match that he knew Shkodran Mustafi and Gabriel Paulista would be left isolated proved the final straw. If Arsenal are going to leave their centre-halves to fend for themselves, they might as well improve their chances by adding another one to the mix. What’s more, including three central defenders inevitably makes Arsenal more defensively secure at set-pieces.

Fielding three centre-backs also means the likes of Koscielny and Gabriel to leave their post at the back and push up into midfield to win the ball higher up the pitch. This enables Arsenal to turn over the ball in more dangerous areas, while the two covering defenders mean they’re less exposed when they take that gamble.

Arsenal have the personnel to make the system work. Koscielny is at his best when given license to carry the ball up the field, while the introduction of the startlingly composed Rob Holding to the side is a very welcome one. When Mustafi and countryman Per Mertesacker are available for selection again, they’ll both presumably look more comfortable in a back three than they would in a two.

Alex Oxlade-Chamberlain filled the right-wing back role against Middlesbrough, but in the longer-term Hector Bellerin seems a natural for that particular position. Having three centre-backs also means Arsenal can afford to play without a true holding midfielder, enabling them to finally dispense with Francis Coquelin.

In attack, it liberates Mesut Ozil and Alexis Sanchez to operate with considerable freedom behind a lone striker. With Danny Welbeck having succumbed to injury once again, that’s likely to be Olivier Giroud, who will be looking to thrive on crosses from the over-lapping wing-backs.

The new system is something of an unknown quantity, but that could be to Arsenal’s advantage this weekend. If they field it against Manchester City, Pep Guardiola won’t necessarily know what to expect. Arsenal—and perhaps Wenger—have suddenly taken on an air of unpredictability.

A win over Middlesbrough does not mean that Arsenal have turned the corner. However, as Wenger intimated after the Riverside game the new system has given fans and players alike something to believe in. Reverting to type at Wembley would send a strange message. Having found something that looks as if it could revitalise an ailing side, Arsenal need to persist with it.