After replacing Brendan Rodgers in October 2015, Klopp made do with the players he inherited with the exception of, somewhat bizarrely, Steven Caulker,who joined on loan from QPR the following January.
Rather impressively, Klopp managed to steer Liverpool to two cup finals in 2015-16 but defeats to Manchester City in the League Cup and Sevilla in the Europa League allied to a final Premier League finish of 8th (below West Ham and Southampton) demonstrated the need to strengthen in the transfer market.
Mourinho, meanwhile, took charge of a side that had finished three places above Liverpool but only by six points as Louis Van Gaals failure to secure Champions League football resulted in him being released from his contract a year early, despite winning the FA Cup against a dancing Alan Pardew.
Both managers, then, had plenty of work to do in order to restore Englands two most historic clubs to a level befitting their statuses. Both managers had similar challenges to face: both clubs were in the Europa League at the time of their appointments, both had bloated squads filled with underperforming players and both were suffering from an identity crisis.
During his first season in charge, Mourinho even emulated Klopp by reaching the finals of the League Cup and Europa League, yet unlike Klopp, he managed to win them, beating Southampton and Ajax.
Since then, though, Liverpool have steadily closed the gap on their rivals, both domestically and in Europe, while United have meandered in the opposite direction. Ahead of Sundays meeting between the two at Anfield, Liverpool are 16 points and five places ahead of United in the Premier League table. A seismic gap at this stage.
It would be too simplistic to pin Liverpools success and Uniteds struggles over the past few months solely on player recruitment made by both, yet it has undoubtedly been a significant factor in creating the chasm between the two.
While Klopp has generally bought well, Mourinho has largely not. Both have enjoyed the luxury of splashing record-breaking levels of cash, but while Klopps budget-busting recruits have succeeded or shown signs that they will succeed, Mourinhos largely havent.
Before Chelsea signed Kepa Arrizabalaga for £71m, Liverpool had both the worlds most expensive goalkeeper and the most expensive defender in their ranks. The £75m and £67m fees spent on Virgil Van Dijk and Alisson looked steep at the time yet between them the pair have vastly improved a previously sieve-like defence. After his heroics against Napoli, Klopp said that he would have paid double for Alisson, had he known how good he was.
In contrast, Mourinhos headline recruits havent yet offered value for money. The £89m capture of Paul Pogba from Juventus in 2016 broke a world record transfer fee that had stood for three years – the £85m Real Madrid sent Tottenhams way for Gareth Bale – and was seen as a serious statement of intent given the Frenchmans reputation.
Pogba played an important role in Uniteds double success in 2015-16, yet since then he has faced a barrage of criticism covering a number of different topics, ranging from on-field issues such as his lack of goals, assists and consistency as well as tactical inflexibility, to off-field matters such as *sigh* the haircuts and the dabbing. A difficult relationship with Mourinho has further cast a grey cloud over the deal.
Alexis Sanchez might not have cost United a transfer fee, joining in a rare swap deal with Henrikh Mkhitaryan moving in the opposite direction, yet he has cost United a mind-boggling amount of money in wages.
Revelations from Football Leaks earlier this year claimed that Sanchezs basic wage is £391,000 after tax, while he also reportedly has a number of lovely little bonuses too, including £75,000 for every appearance he makes. If that basic wage is correct, Sanchez has earned £17,986,000 since joining United in January. Or around £4.5m for every goal he has scored.
In August, Mourinho to the accompaniment of the worlds smallest violin (presumably) lashed out at Klopp and his age-old adversary Pep Guardiola for spending too much money on transfers. Mourinho declared that Liverpool were trying to buy the title after their signings of Alisson, Naby Keita, Fabinho and Xherdan Shaqiri.
Although Mourinho has a point that Liverpools spending has soared over the past few windows, it isnt as if he has had to operate with his hands tied. Although Klopp has spent approximately £405m on players spread out over six transfer windows (around £67.5m per window), Mourinho has had £365m to play with (around £73m per window).
Klopps transfer budget has also been swelled by the mega-money sale of Philippe Coutinho to Barcelona for an initial £105m rising to £142m not to mention the sale of a number of fringe players (£15m for Jordon Ibe anyone?). Uniteds biggest sale during the Mourinho era was Morgan Schneiderlin to Everton for £24m in January 2017. Klopp has recouped far more money than Mourinho has on players he didnt want or need.
Aside from net spend, Liverpools costly signings have largely proven to be value for money. Virgil Van Dijk (£75m), Alisson (£67m), Sadio Mane (£36m), Georginio Wijnaldum (£25m) and Andrew Robertson (£8m) are all important first-team regulars. Thats before even mentioning Mohamed Salah, who at £39m represents an incredible bargain in an age where transfer fees have gone through the roof.
Uniteds signings just havent had the same impact. Henrikh Mkhitaryan (26.3m) was bombed out after 18-months, Eric Bailly (£30m) has regressed after an impressive debut season, Nemanja Matic (£40m) has faded badly after a promising start and Victor Lindelof (£32m) endured a nightmare first year in English football before showing signs of improvement. The less said about Fred (£52m), meanwhile, the better, judging by his Kleberson-esque first six months in the North West.
Then there are the two standouts: Paul Pogba (£89m) and Romelu Lukaku (£75m). Although neither can be regarded as a flop neither has lived up to expectations. Mourinho has even avoided picking them in recent weeks. Pogba has shown flashes of his undoubted class but all too infrequently, while Lukaku has too often appeared to be operating on an entirely different wavelength to that of his teammates.
Although Mourinho out-numbers Klopp for trophies won since taking over at Manchester United, a fourth Premier League title for the Portuguese is out of the question. Despite the money spent, United are as far away from challenging for the title at any point during the difficult post-Sir Alex Ferguson era.
Liverpool are top for now but considering their main rivals for the title happen to be the competitions most dominant side in history, it would be a genuinely colossal feat if they were to end the campaign in their current position.
Even so, that they are in the reckoning at all highlights the excellent work done by Klopp in the transfer market. How Mourinho must wish his signings had made a similarly transformative impact.
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