
The Manchester United midfielder was the only outfield member of England's squad not to get any game time in North America, despite Thomas Tuchel making numerous changes during the tournament. Mainoo would have been expected to at least figure in the bronze medal match against France, only for him to be ruled out with a back injury.
Mainoo's lack of minutes, especially when England struggled to retain possession, left many puzzled. Former United midfielder Nicky Butt went so far as to say Mainoo should have refused to play against France because of Tuchel's treatment of him.
Meanwhile, former Neil Warnock has called out Tuchel for reportedly criticising Mainoo's training performances. The former Premier League boss told talkSPORT: "You don't say that to the press.
"You put an arm around him and say, 'Look, you're not training so good, son. Can you lift your percentage up?' Things like that should be kept inside the camp."
While it has been a forgettable tournament for Mainoo, it is not uncharted territory, given that he was frozen out by Ruben Amorim before his sacking in January. Having looked set to leave the club, Mainoo was brought back into the fold by Carrick.
His form over the second half of the season was so strong that he signed a new contract and looks set to be a key player during Carrick's first full season at the helm. The United boss said restoring him to the side was a straightforward decision despite his lack of minutes.
He told the BBC last season: "I've known Kobbie a long time. I started working with him when I think he was 13 or 14, when I was starting to do my coaching badges.
"And then when I was here the first time [as a coach], he was in and around a little bit. So I think knowing him and having experience with him and seeing him perform at such a level on such big occasions [is important]...What Kobbie's done at such a young age is quite incredible really.
"We forget how young he still is. I was just a big fan of watching him play and knowing what he was capable of. So it wasn't really a big decision to play him."
"There are things he can get better at, things he can improve on, but we haven't really got started on any of that because we're just letting him go and find his flow.
"I've been really conscious of not giving him an awful lot - a couple of little pointers, a bit of positional things and some little bits here and there - but trust in what he is. He's a fantastic footballer and he's got a huge talent."