Bonucci is improved by Sarri's system. Bonucci doesn't have to man mark, just watch the ball. The whole line moves in accordance to the position of the ball and they use the trap very well. These are all things that have suited Bonucci for his whole career because his anticipation is GOOD. Bonucci is comfortable with watching the ball as the team in front presses. He can anticipate where the opponent will play and always has been able to, as long as the opponent is under pressure.
This is what MDL had to adapt to (I could be mistaken but I don't think Ajax played this way. I think they pressed fine but preferred to man mark) and now is a complete monster. Probably already one of the best CBs in the world. If he puts himself in the proper position in accordance with the defensive line, I don't see how an attacker can pass him.