I think we're all seeing mistakes, but we're only half-way into the trial. Also he's 23 and he has a different CB, LB or RB partner and position every week.
He doesn't just have pace but he's very good at anticipating and intercepting passes as well. He makes errors, but I don't see him shut off mentally. He's quick to recognize and rectify mistakes from not only himself but also others which shows he's mentally sharp as well.
The Manure goal... That could've been, and usually would be easily prevented with an offside trap. However Dalot was watching the ball while keeping Diallo onside, oh and he was instructing Krunic to keep an eye on Diallo while Krunic was watching the ball as well. Tomori spotted the run into his zone early and could've done better in that situation once he was ahead of Diallo, but that goal was more on Donna and Dalot.
I'm not concerned about him getting caught out of position. Our defenders are instructed to be aggressive and break plays at an early stage, and he's been better at it than our other CBs. Also he has recovery pace, unlike Romagnoli and Kjaer who've been caught out of position as well.
What's making me doubt that the club will use the 28m option is how error-prone he's been with ball possession so far in his career, but, even more, his difficulties in dealing with balls in the air. There were numerous examples of it in the Manure games, and also in previous appearances.
However he's an English CB. The Milan experience alone will probably do wonders to his market value among EL clubs. If we sign him I don't think we'll make a loss on him unless there's injuries.