They don't though. And on the rare occasions they do, they're going like 75% speed while they rehab an injury or just get a little exercise.
I just looked at the last five games Gomes played in the U23s for United. The sum total of first team player experiences in those matches was one game by Pereira and one game by Rojo. Everybody else is a youth player.
I didn't realize his contract situation. That's certainly a reason not to loan him, but I think my points all still stand about his likely readiness for senior football. He certainly looks like a talented player but its not just about talent when you make this jump.
They do often enough. Even at a lower speed they don't magically lose their strength in duels. Add in all the 21-23 years with lower league experience fighting for spots who play even more physical and dirty than is even allowed in the Premier League. u23s football is far dirtier than the PL. Angel will face nothing like the way he was kicked about last season.
You're not even looking at the right teams, you don't get into physical duels with your own teammates. Who is playing for United is irrelevant, in fact it is just a better point for Angel as it shows he didn't have senior players to rely on, he was the star and talisman who was relied on to take it to the opposition and he did it successfully in 99% of matches.
He's played in his time against countless grown men and you can count on one hand the number of times he's been muscled out of a game. In fact, it has practically never happened even once. There is no need to downplay that as 4 competitive games.
In the last year or so, below is a list of some players with their age when played against and their experience at the time.
Moses Makasi - 22 years old with ~10 senior appearances
Martin Samuelson - 20 years old with ~45 senior appearances and a full Norwegian international
Toni Martinez - 20 years old with ~45 senior appearances
Rene-Adelaide - 20 years with 8 appearances for Arsenal's first team and days later went on loan to Ligue 1 making 10 appearances that same season
Mavropanos - 20yrs with 20 senior appearances
Pleguezuelo - 21 with 15 senior apps
Kylian Hazard - 22 with 42 apps
Cauley Woodrow - 23 with 120 appearances
Mattias Kait - 20 with 15 full caps for Estonia
Harry McKirdy - 21 - 30 apps
Jordan Lyden - 22 - 6 apps for Villa but a physical DM that Angel was up against
James Bree - 20 - 80 apps. RB who Angel was up against playing on the left side
Jake Hesketh - 22 - 40 senior appearances in the same season
Yan Valery - 19 - again the RB who Angel came up against playing on the left. 23 PL appearances in the same season.
Charlie Adam - 32 - 385 apps. Angel out muscled him, made a mug of him and had his legs swiped out by Adam on 3 occasions. Is trying to injure a playing taking it 75%?
Moritz Bauer - 26 - 150 apps. Angel drifted left a lot and made a mug of him too
Callum Harriot x2 - 24 - 130 apps
Max Kilman - 21 - 70 apps plus an England futsal national
Dominic Iorfa - 23 - 120 apps. The entire Wolves side on the whole was older and very physical and disciplined. Was a great test that Angel did well in.
Sean Longstaff - 21 - 60 apps and months later playing in the PL and getting linked to us for 50m
Adrian Popa - 30 - 450 apps
Nathan Collins - only 18 but a mountain of a lad who has already captained Stoke's first team and was linked to us
Wes Hoolahan - 36 - over 500 apps
Jefferson Montero - 29 - 400 apps
Sam Field - 21 - 40 apps
Jamie Sterry - 23 - 40 apps
So that is combined experience there of over 3000 senior matches plus there were a bunch of other 20-21 year old with 10-20 senior apps which I couldn't be bothered writing down. Add in all the apps these players made after playing Angel too. Not like Longstaff suddenly become 10x better a month after playing Angel. Add in his first team cameos, the pre-season, BHC matches such as the Sheffield one, the EFL trophy against Rotherham. All in all he has played against countless fully grown adults who aren't youth players.