LB: Benjamin Mendy | Manchester City | €57.50m
Pep Guardiola suffered his worst-ever league finish in the 2016/17 season, due to which he wanted to oversee a thorough revamp of the squad. He spent heftily on the full-back area, and as part of this expenditure, City purchased AS Monaco star Benjamin Mendy for €57.50m in the summer of 2017.
Mendy has endured an absolutely shambolic time in Manchester so far. The Frenchman has missed over a staggering 80 games via injuries since he arrived in the Premier League, and even when he has played, Mendy has left a lot to be desired. His lack of defensive awareness and knack of getting beaten by opposition wingertime and time again saw him lose his place to Oleksandr Zinchenko and, more recently, Joao Cancelo in the XI.
Unless the 26-year-old's career sees a drastic turnaround, Mendy's record purchase from Monaco will go down as one of the worst signings in recent history, as he's offered little to no impetus to this City side.
CB: Virgil van Dijk | Liverpool | €84.65m
Eyebrows were raised when Liverpool made the decision to shell out a world-record fee for a defender to sign then-Southampton centre-half Virgil van Dijk. The Dutchman, who cost the Reds a staggering €84.65m at the time, has since gone on to establish himself as the best central defender in world football.
The transformative signing enabled them to build a team that achieved success across both domestic and continental fronts. Liverpool won the UEFA Champions League in 2018/19, and Van Dijk was adjudged the best player in Europe for his immeasurable impact on the six-time European champions. The 29-year-old then guided Jurgen Klopp's men to their first-ever Premier League title in 2019/20 with the best defensive record in the top-flight.
Van Dijk's world-record purchase for a defender at the time has proven to be one of the most successful and transformative signings in all of football history, let alone that of the Premier League.
CB: Harry Maguire | Manchester United | €87m
Manchester United ditched their well-documented pursuit of Napoli's Kalidou Koulibaly to sign English defender Harry Maguire for a world-record fee in 2019. The former Leicester City man was made the most expensive centre-half in the world after the Red Devils purchased him for €87m last summer.
Although he is yet to have a Van Dijk-esque impact on Manchester United, Maguire's defensive prowess has been at the fore for the club, as seen by their improvement in defensive numbers. The Red Devils conceded 54 goals in 38 league games last year, a number which the 26-year-old has helped limit to 36 this year. He was made captain in the wake of Ashley Young's departure and has been a reliable figure for Ole Gunnar Solskjaer's men, who finished third in the Premier League in 2019/20.
That being said, there is a feeling that Maguire is yet to justify why Manchester United parted with a surreal amount of money for him. They are reportedly looking for a pacey centre-half to pair with Maguire for the 2020/21 season.
RB: Kyle Walker | Manchester City | €53m
The second Manchester City defender on this list, Kyle Walker was briefly the most expensive specialist full-back in the world, until City broke their own record just days after to purchase Mendy. However, Walker's time at Manchester City is unrecognisably different from that of Mendy's.
The Englishman has grown into a pivotal figure for Pep Guardiola's defence, proving why City were insistent on signing him from Tottenham Hotspur. Walker has been utilised by Guardiola in both roles, as an attacking full-back and as an inverted one, and both have helped him reap the rewards of Walker's ability. He remains one of the quickest full-backs in the Premier League, and his intelligence allows him to be deployed in various set-ups with varying responsibilities.
Walker has mostly been an undroppable figure for Guardiola and City, regularly putting in tireless shifts for his side. His consistency has been remarkable, and Walker has been one of the better of City's plethora of signings in recent times.
Also read: 5 Best signings made by Pep Guardiola at Manchester City | Premier League 2019-20