Except it doesn't work like that. It's never the match days that actually decides someone's career. If that was the case , there would never be brilliant players from teams coached badly than ETH or United.
Match days, coaching, whatever. I'd argue that a lot of our players play how they do because they've not been drilled into playing a good brand of football at all. They don't have the instincts to rely on because they're not doing it week after week, and when they're tested on the pitch their game falls apart. Does it stay with them forever? Maybe. Does it mean we don't get to see these players reach their full potential? It's hard to prove either way. But when I see Bruno and what he does instinctively, even when he should ignore his instincts, that's because he's being asked to do that week after week. If he'd have gone to play under Klopp, for example, or Pep, I think you'd have seen a much more well rounded player than you have now.
Even going back to Fergie's time, look at how he handled prodigal talents. Ronaldo is an example of a player that could have easily been ruined playing in a worse team or under a manager that didn't steer him properly.
I think Hojlund and Garnacho are players at higher risk of not developing here, because they're relied upon for their physical abilities and when that's nullified, they're completely lost. Rashford is a perfect example, he's been taught to run as fast as he can with his head down, shoot on sight etc. Now teams have figured his one dimensional style out, he can't seem to come up with anything else. Give him space in behind and that's what he's taught to feed on. Close his space and block him on the inside and he's ineffective.
I could guarantee that if Pep had Mainoo, he'd look even better. He's operate when pressed better, he'd control games more, he'd probably be even more of a goal threat too.