I am not sure that is true as evidenced by his time at Napoli. He took over from Sarri who played a high pressing 4-3-3. That clearly suited the players as they almost won the League in Sarri's last season. Ancelotti then changed that to a 4-4-2 mid block.
He has spoken about himself he says he has become less rigid but is still a 4-4-2 man at heart.
He finished 2nd with Napoli in his first season so it looks like the change didn't do them too bad did it?