The tactical landscape of the Premier League was very different when Manchester United dominated England's top-flight under Sir Alex Ferguson, with 4-4-2 widely regarded as the most effective formation in the playbook.
Roy Keane and Paul Scholes developed a reputation for their quality as a two-man pairing in the middle of the park. The two players were able to complement each other's strengths and weaknesses for years at Old Trafford.
Gradually, continental ideas began to shape English football. Pep Guardiola's Barcelona team in particular had a notable influence on conventional wisdom, with his favoured 4-3-3 system delivering a whole host of trophies at the Camp Nou.
The midfield trio of Xavi, Andres Iniesta and Sergio Busquets governed Europe's elite competition and prevented Ferguson from winning two separate Champions League finals in 2008/09 and 2010/11.
Years later, the popularity of 4-3-3 as a go-to formation would increase further thanks to the arrival of Guardiola on English shores alongside Jurgen Klopp, each of whom would implement their own versions of the shape at Manchester City and Liverpool.
As a consequence of the tactical shift, United have been increasingly encouraged to move towards 4-3-3, but it has become increasingly difficult to identify players for the lone holding midfield role who are complete enough to perform for a top club such as United.
The likes of Fabinho, Fernandinho, Rodri and Busquets rank amongst the very best, but they can be difficult to source.
Since Ferguson's retirement, the Red Devils have refrained from picking up a lone holding midfielder from the transfer market. Instead, a midfield two has been preferred, with Ralf Rangnick surprising many by following a similar path.
The German coach has taken charge of two matches so far but rather than getting rid of Ole Gunnar Solskjaer's midfield two - which was recognised as a problem by many supporters - he's changed other elements to move from 4-2-3-1 to 4-2-2-2.
His relatively uncommon 4-2-2-2 system seems to suit the players at his disposal and if he's willing to settle on that shape for the rest of his tenure, it could benefit United's midfield department while also aiding the club's scouting efforts.
Midfielders linked with transfers to United, such as Declan Rice and Aurelien Tchouameni, are accustomed to playing as part of a duo at West Ham United and AS Monaco.
Despite the murmurs of United embracing the new-found obsession with 4-3-3 earlier in the season, Rangnick's 4-2-2-2 solution could save players such as Fred while also encouraging bids for the likes of Rice and Tchouameni.
In the coming months, United will find out whether their midfield two was truly to blame for their downfall under Solskjaer, or whether it can form part of a functional setup.
