I agree that if you haven't watched any of a player's development, it's a bit rich to see three senior games and then declare definitively what they can and cannot do.
That said, there's also validity to pointing out that many players never really manage to reproduce the kind of football they were known for as kids once they get into senior football.
From Hannibal's perspective, I'd say Andreas Pereira is a really good cautionary tale here. We brought him in as a highly-rated 15/16 year old with lots of big European clubs sniffing around. He was known for his ball control, his vision, his raking diagonal passes, his ability to carry the ball in tight spaces, his dead ball delivery and his shooting from range. A real rolls royce player. He could also really tackle which at the time was always noted with surprise from flair creative players. His weakness was his lack of urgency and work-rate - he would sometimes drift in and out of games where he was evidently the most gifted player on the pitch and should have been dictating.
In the first team, having trawled his way through two years of non-very-successful La Liga loans, his work rate and application were much improved, and that knack for a tackle was still there. But he couldn't establish himself in games with the confidence to produce all the stuff he was known for as a kid. Fans who'd never really seen him before appreciated his graft but pointed out that he didn't seem to offer anything else; they wanted players with technical quality and creativity. Those who had watched him from the start through U18s and U21s grumbled, knowing that was meant to be his whole deal.
If you watch him for Fulham now, he's starting to settle and become the type of player he was as a youth again. Creativity, vision, long passing, crossing and free-kicks. But he never managed to show it at United.
Hannibal should be wary of this. He's produced the things Ten Hag wants first and foremost - work rate, positional discipline, fitting into the system. But he should quickly look to build on that and reproduce what the reserves-watchers know he has in his locker: progressive ball-carrying, aggressive passing, goals and assists. It doesn't take long to accidentally slip into a pattern of hard-working mediocrity.
