1. You can't completely profile a player after one game or just one action, but it's often enough to determine whether they have specific traits or not. Just one game or action can say a lot, even if it doesn't tell you the whole story.
2. Yoro was considered a generational talent by every single detailed scouting report you could find on him when he was still at Lille. Liverpool also viewed him as the best long-term replacement they could possibly find for van Dijk. Madrid's chief scout Juni Calafat viewed him as the Mbappé of CBs. He was also PSG's and United's primary CB target out of everyone on the market. You can probably presume that every other top club that kept tabs on him had a similar opinion on the player, even if their interest never really materialized into anything serious, which could've been down to many things (financial issues, not needing a CB, or thinking they didn't have a chance to snatch him away from Madrid).
The reason Madrid didn't pay up for him was because:
-They spent a lot of money already on Mbappé's sign-on bonus, Bellingham, and Endrick, all within 12 months' time, which was probably a ~€250m or bigger financial outlay combined for those three
-They probably didn't think that a project CB was worth that much already at 18, because when you buy raw talents with incredibly high ceilings like Yoro, you take responsibility of their development, and you need to make sure that they have the right coaching, right team environment, right role in the tactical system, right amount of responsibility on their shoulders, and that their mental development as human beings also goes well. United decided to not only overpay for the player, but to take on all these risks as well, which is admittedly a risky move, but it's also highly ambitious, and it doesn't discredit the player's talent. In fact, it does the opposite.
It's like Arsenal paying 50m for an 18 year old Saliba when he was at Saint-Etienne. Yes, even that fee would've been a bargain in hindsight, because today he would be by far the most expensive centre-back in the world in an open market, but they didn't pay that much for him, because of all these responsibilites and risks I mentioned.
Sadly, Yoro's development can easily deteriorate at United, the same way as that happened to many wonderkids and world class talents we had at the club in the last 12 years. However, that doesn't change the fact that he was viewed as the next generational CB talent based off of less than 12 months at senior level.
3. Dorgu has played over 50 Serie A games already. That's more than enough for a top club's scouting department to profile a player in detail, and also make an educated guess about what their ceiling could be and what kind of player they can grow into.
Dorgu looks like a really promising player who can become a similar full-back / wing-back to Alphonso Davies and Nuno Mendes, mostly because he's has a similarly exceptional athletic/physical profile to them. But if we buy him, it will be United's responsibility to make sure he gets there within 2-3 years' time.
So whilst I think the player's potential is clear, he would be a project signing, which is my only gripe with this signing. The fans won't be patient with him, and will expect immediate impact from a young player that's still raw and will make mistakes. All because of his price tag. I also don't have a lot of faith in the club handling his development well, based on the last 12 years.
However, if we manage to build up all these project players with immense potential, like Yoro, Dorgu, Hojlund, Amass, and to an extent, Mainoo, Amad, Collyer, etc. and many prospects still in the academy, then we will be one of the best club sides in world football within 3 years, because the raw talent is there, we just need to not mess it up...
...but it's admittedly a very questionable approach. And it's a bit similar to what Chelsea have done by stockpiling dozens of young talents for big money under the new ownership. How can a top biggest 3 club in the world (United, not Chelsea, obviously), with sky high expectations all the time, give these young players multiple years of patience, reduced responsibility to make an immediate impact, and the required development in all aspects, when they're already the first choice players in their positions?
I'm willing to be patient because I'm aware of the situation, and know that these signings like Hojlund, Yoro, or Dorgu massively raise the ceiling of United's football project, but maybe not the flooring immediately.
Also, many fans are impatient and don't realize the situation I've just described. Hojlund has already been labelled as a flop despite being one of the most exciting U23 striker prospects in the world, Mainoo can have 1 bad game after 9 great ones, and he's questioned too, Yoro had 1 bad game vs Southampton, and idiots on Twitter are already saying he's not as talented as he was made out to be, etc. We don't even have a stable, well-drilled team that can compete for top 4, which would be the minimum requirement for these young players to grow into the players they can become.
A better approach would be to find older, more experienced and more established players for cheap, like Mazraoui, who can come in and make an immediate impact, "raise the floor" of the team, whilst the talents we pay a premium for because of their potential, would be rotational players, and could focus on their development at least in their first two seasons, with reduced external pressure to perform to a consistent and high level from day 1 straightaway.