Well, as I said before he joined, this was pretty much how he played at Ajax. He struggled to beat his FB there, ruined plenty of counter attacks due to either not trusting himself to carry the ball or needing to always cut in on his left whether it was the right time or not, nearly always looked to cut in and shoot, didn't have a good cross on him, etc.
The two big differences were that the league was obviously weaker than the PL, and Mazraoui completely dominated the right which gave Antony plenty of leeway.
Though, for the Brazilian youth teams I saw, he was much more impressive. Along with Arsenals Martinelli and Matheus Henrique, he was always the most impressive player on the pitch. He was more direct, was beating his FBs, using his right foot more. That's what still gives me hope that he can become a good player. Not this explosive winger most thought we were getting, but, if he improves his strength, a good playmaker who can chip in with some goals.