It's hard to think about exactly what kind of midfielder is needed to be honest. Obviously he must replace Rabiot, he must be able to hold the ball, dribble, pass and shoot well. Rabiot tackles and runs in a straight line fairly quickly. That's about all. A lot of hype about his technique. I really don't see any examples of excellent technique on his part.
I thought Locatelli would solve things as a regista. Then it looked like purposeful movement was the missing element - Zakaria looks like he can provide that. But even if Zakaria is relatively successful, I can't see him joining the midfielder to the damned forwards.
I'd like to see Arthur play as Mezz'ala. That is one of Allegri's stupid nostrums (there are a few others that are probably to blame) - he would prefer to play these less defensive minded mids central and deep. Exact same situation as Pjanic except of course Pjanic played with a better midfield and it worked out, but I think Pjanic would have been even better for us as a mezz'ala. Even in the diamond around 2012/13, Vidal played in the hole. That was Allegri's intention for McKennie early this season. Why not Arthur? Didn't Isco tear us up in 2017 playing as an advanced mid? Isn't it just common sense?
We probably did need a new manager but we chose really poorly, not that it's ever easy. Allegri just has too many silly ideas that impose limits us. He had historical success because he imposed his ideas on a squad that was suited to them, and he was pretty flexible throughout his time. But as well as the above example, he has always insisted that a team can't press or hold the ball for long periods of the game. It's his plan to sit back and not hold the ball for intermittent periods of games. He doesn't say expressly that it's to conserve energy (which wouldn't make sense) but he does say that there are inevitable "moments" in games, meaning momentum swings. So, simply give in and allow for the apparent inevitable. It's a fatalistic, absurd idea that gives the other side a look in and doesn't grasp the fact that momentum shifts in favour of the opposition are neither inevitable nor desirable.