Now, with the transfer to Juventus, Di Maria likely is experiencing the last seasons he play in Europe at highest level. I don't expect too much from Di Maria because he is very old and with old players, contribution is affected a lot after each season.
You are right. Real Madrid didn't give Di Maria enough respect. He was an under rated player at Real Madrid. Because Madrid had a lot of star players. It is very difficult to survive with them. Then we saw the same thing at PSG. With so many star players in the squad, Di Maria was not that important to the PSG management. Now is Di Maria's chance to become the most important player in the Juventus squad. But we don't know if he will succeed.