As managers search for a winning formula, they require their players to be adaptable. Now that Premier League football is no longer entrenched in a 4-4-2 orthodoxy, versatility has become a requirement.
The ESPN FC team suggest five players who have flourished in an unfamiliar role this season.
James Milner (Liverpool, left-back)
Having joined on a free transfer in the summer of 2015, Milner reportedly earns £150,000 a week at Liverpool and is one of their best-paid players. He was signed by Brendan Rodgers to play in central midfield, an experienced head who might offset the loss of Steven Gerrard. Milner left Manchester City despite being offered a higher wage because he wanted to play as a midfielder.
Jurgen Klopp's arrival last October looked ominous for Milner, who never managed to convince the German of his aptitude for his desired position, and was usually pushed out to the flanks last season. Then came Liverpool's failure to sign a top-quality left-back, and a near-disastrous showing by Alberto Moreno in a season-opening 4-3 win at Arsenal. Milner was immediately thrust into the left-back position, and despite the unpromising beginning of a 2-0 defeat at Burnley on Aug. 20, he has never looked back.
Despite being a first-teamer since he was a 16-year-old at Leeds, Milner retains his engine and a smart football brain -- as well as being deadly from the penalty spot, with five from five attempts this season. Left-back is no longer a problem position for Liverpool.
Victor Moses (Chelsea, right wing-back)
The sight of Moses making a lung-bursting run to convert Chelsea's second goal in their 2-1 defeat of Tottenham last Saturday was symbolic of the transformation in the Nigerian. Since signing for the club in 2012, he had been a Stamford Bridge spare part, appearing lost within his parent club's labyrinthine loan system, enduring not particularly satisfying spells at Liverpool, Stoke City and West Ham.
He also admitted to ESPN FC in October that he and Jose Mourinho had hardly exchanged a word. But Antonio Conte's arrival and adoption of his favoured 3-4-3/3-4-2-1 formation has altered Moses' Chelsea career beyond all recognition. Wing-backs have not been in fashion in the Premier League since the late-1990s, but Moses, previously a winger, looks ideal for the position, able to exert his speed down the flank, with his physical power an asset to Chelsea's defensive efforts.
Once the forgotten man, he has become a fan favourite.
Cesar Azpilicueta (Chelsea, centre-back)
When a coach makes the decision to reconfigure his team, as Conte did while his side were 3-0 down to Arsenal on Sept. 24, he requires his players to be adaptable. Azpilicueta has always been versatile, having played at both left-back and right-back for Chelsea, with little variance in the quality of his play.
He had not played as a centre-back since leaving hometown club Osasuna in 2010, but Conte fielding him as the left-sided member of a trio has brought startling results. The ravishing strike that Christian Eriksen scored for Spurs last week was the first Premier League goal Chelsea had conceded since that Arsenal defeat -- seven matches. Poised and dedicated, Azpilicueta has formed a redoubtable, organised partnership with David Luiz and Gary Cahill.
Ander Herrera (Manchester United, midfielder)
Herrera has always been a midfielder by trade, but the player Manchester United are seeing now is not the playmaker David Moyes tried to sign from Athletic Bilbao in 2013, and eventually joined the club under Louis van Gaal's stewardship the following year. United were looking for a classy midfielder, someone to dictate play, or perhaps even play off the striker.
Van Gaal certainly tried him at a variety of positions, without ever trusting him fully at any of them. Jose Mourinho, though, appears to have altered Herrera's bearing. Despite his slight frame, Herrera has become United's enforcer, tough in the tackle, a leader noticeably vocal in encouraging teammates. Of any of United's players, it is Herrera who most seems to personify the motivated, often cynical approach that Mourinho's most successful teams exhibit.
Alexis Sanchez (Arsenal, striker)
No list of reinvented players could be complete without Sanchez, tearing it up for Arsenal since stepping into a striker's role when Olivier Giroud's return was delayed after Euro 2016.
Sanchez occasionally played as a striker for Chile and Barcelona but was long considered as the powerful winger who made his breakthrough at Udinese. But Arsene Wenger has fielded him as a central counterpoint, ahead of three attacking midfielders.
"I like getting involved in the play more rather than chasing the ball," Sanchez said last week. "I like seeing lots of the ball because I have the chance to drop deep, and that means I can link up with my teammates more."
He has the energy levels to fulfil those functions. Last season's scoring drought, when he went 140 days without a Premier League strike, is long forgotten. He has rattled in 10 goals this season.