As Casemiro left the Old Trafford pitch last weekend, he knew it was the last act of his four years as a Manchester United player.The emotional, slightly teary send-off in the closing stages of a 3-2 win against Nottingham Forest had been pencilled in as his curtain call earlier this season.Rather than travelling the 250-odd miles to Brighton for a campaign-ending fixture now of little consequence for coach Michael Carrick’s side, it was agreed that, so long as United could not finish in a higher league position, his last appearance for the club should be at Old Trafford.After all, that is where, since announcing his impending departure in January, every game has felt like another leg in a long farewell tour. Seven of his nine goals this season have come in home games. The same number have also either put United ahead in the match concerned or brought them level.Michael Carrick embraces Casemiro following the Premier League match against Liverpool earlier this month (Michael Regan/Getty Images)He has not just scored goals, but important ones, while rolling back the years at age 34 on his bread-and-butter abilities as one of the best holding midfielders of his generation.Still, the adulation shown by match-going United supporters towards Casemiro may come as a surprise to some.A minimum £60million ($80.6m at the current rate) signing, who arrived from Real Madrid as a 30-year-old on a salary of up to £350,000 a week, will leave with two domestic cup final wins and two Champions League qualifications from the possible four, but with the blemish of eighth- and a 15th-place finishes, and several hard-to-forget horror shows in between.Pilloried as the type of expensive, starry-eyed signing United have been guilty of making too many times upon his arrival, even after this late renaissance, that record does not scream value for money.Some who have worked with Casemiro during his time in Manchester would argue you cannot put a price on his very best qualities, however.“The character, the aura, the presence, the determination,” says one, speaking to The Athletic anonymously to protect relationships, as with others in this article. “Characters like that are what Manchester United is, in my opinion. Not ‘perfect’, but determined, cooperative, passionate people that love the club. He’s embodied that — these last two seasons especially.”After a protracted and ultimately unsuccessful pursuit of Barcelona midfielder Frenkie de Jong, some at United believed they were signing a very different player as an alternative to new manager Erik ten Hag’s first-choice target that summer of 2022. Less of a connector, more of a destroyer.Yet after years of watching him carry water for Toni Kroos and Luka Modric at Madrid, possibly the biggest surprise upon Casemiro’s arrival was his ability on the ball. From the first few training sessions, those on the ground began to recognise that here was a signing who could make plays as well as break them up.Casemiro had been used to lifting trophies with Modric and Kroos at Real Madrid (Alex Grimm/Getty Images)An understanding quickly formed with Bruno Fernandes, who learned that a pass inside to Casemiro would reliably result in a ball played through the lines and in behind a defence.It is a connection that has endured, albeit with Fernandes as provider — the pair have combined for six of Casemiro’s nine goals among Fernandes’ record-equalling 20 assists this season.That quality on the pitch was matched by an attentiveness off it.As at many Premier League clubs, United’s players are provided with WyScout clip packages of their displays after every game, typically running to a size of two to three gigabytes. Casemiro’s would regularly stretch to 30GB.There was a time at United, under the management of Louis van Gaal, that players would ignore such email attachments and just mark the messages as read, but Casemiro’s eagerness to review every aspect of his performances meant post-match debriefs would be followed by questions and comments.The individual highlight of an impressive debut year was the Carabao Cup final win against Newcastle, in which Casemiro scored the opening goal, with the type of towering header from a set piece that would become his stock in trade for the club.