Shadow of De Bruyne hangs over Mourinho and Martial
When the result doesn't go their team's way, managers will often talk about "individuals" as a method of deflecting the blame away from their own work.
Usually, the reference is to "individual errors" which is closely followed by "that you can't legislate for". In other words, the manager did everything that he could on the training ground, but a player let him and everybody else down.
After the defeat to Brighton, Jose Mourinho took a slightly different approach with his statement that "we're not as good individually as people think we are". Like most Mourinho statements, it took very little decoding to get to its meaning.
The first part is a clear message to the Manchester United moneymen that they are going to have to dig deep into their pockets this summer.
The second is a subtle method of self-praise. In other words, the players aren't good enough individually, so it must be the manager that gets them to the FA Cup final and to runners-up in the Premier League. It brings to mind Chris Rock's sketch about fathers boasting about taking care of their children because, in this case, Mourinho seems to want credit for something he's supposed to do.
It's unfair to argue that no players have improved in Mourinho's reign and, on Friday, the likes of Chris Smalling, Ashley Young, Marouane Fellaini and Jesse Lingard were involved who have all gone from decent players, to slightly better than decent players in the two seasons that the Portuguese has been in charge. Whether they are of the standard United need to overhaul Manchester City and get back among the elite of Europe is a different argument.
Where Mourinho continues to struggle, however, is to consistently get the best out of players who have the potential to be far more than "decent". Paul Pogba cost almost twice as much as entire the Brighton starting line-up and while the transfer fee isn't his fault, it's not unreasonable to expect a player with his ability to produce a little more than the current one good game/one terrible game pattern.
Nobody doubts Pogba's talent or that of Alexis Sanchez but the suspicion is that both have already reached the peak of their powers - even if it was at their previous clubs - so Mourinho's challenge is to rediscover what he already knows is there. That's the easy bit.
The more difficult part is with players like Marcus Rashford or Anthony Martial that nobody - least of all Mourinho, it seems - knows just how good they can be.
Rashford has a contract for another two years and, even if he isn't part of the immediate plans, there is no way a manager even with Mourinho's self-assurance would countenance selling a 20-year-old who is the current emblem of the historic link between youth team and first team which the club are justifiably proud.
Martial, however, is different and has the ability to damage Mourinho's reputation for player development which has been questioned under scrutiny this season as the Premier League's two outstanding players scarcely got a kick during their time under his management.
Kevin De Bruyne first worked with Mourinho at the age of 21 in the summer of 2013 after the manager returned for his second spell at Chelsea. Having impressed on loan at Werder Bremen in the previous season, Mourinho sold him to Wolfsburg within six months.
"With De Bruyne, if you have a player knocking on your door and crying every day he wants to leave, you have to make a decision," was Mourinho's rather withering recollection of the sale. "He was not ready to compete. He was an upset kid, his training was very bad."
Mourinho has slightly more wiggle-room around Mo Salah when he argues that Salah was sold to Roma after Mourinho had been sacked but, again, it doesn't explain why a player who has subsequently proved to be so talented, couldn't flourish under Mourinho.
Like De Bruyne, Salah was 21 when he first worked with Mourinho and he lasted fractionally longer under him than the Belgian he replaced at Stamford Bridge. A year after arriving under Mourinho, at 22, he was gone on loan to Fiorentina.
Martial doesn't turn 23 until the end of the year and, like De Bruyne and Salah, doesn't seem to be responding particularly well to Mourinho's tough-love approach which makes one imagine a sign hanging above the training ground proclaiming that "beatings will continue until morale improves".
Sometimes players - like Alex Oxlade-Chamberlain - just need to find the right style of team to bring the best out of them but, in Martial's case, it's difficult to believe that he could look as out of place in either England's or Europe's best teams as he has done at Old Trafford, regardless of what way their managers want to play.
He is already a better centre-forward than anyone at Chelsea and would, at a minimum, be an upgrade as an alternative option in the attacking triumvirate at Liverpool or Manchester City, while Tottenham could easily use him as competition for Harry Kane. In all likelihood, Real Madrid, Barcelona and PSG will at least make an enquiry.
With one year left on his contract and unlike De Bruyne or Salah, it's unlikely Martial will be interested in a move to the equivalent of Wolfsburg or Fiorentina, meaning that Mourinho won't be able to put distance between himself as a manager and the player becoming among the world's elite.
Alex Ferguson, Arsene Wenger or Pep Guardiola never had a player leave them because they were surplus to requirements who subsequently became a superstar but, in the right environment, Martial has the ability to follow De Bruyne and Salah in proving Mourinho wrong again.
When Martial signs for United three years ago for an initial £36m, it was a sign of his potential that one of the clauses in the deal was a significant additional payment if he ever won the Ballon d'Or.
That won't happen under Mourinho but four years ago, nobody would believe Salah could one day be in the running either. He just wasn't as good as people thought he was.