Pirlo shined in Milan because he had an offensive AM (Kaka) and two deadly strikers (Sheva and Crespo/Inzaghi) to send long passes. I'm not saying Pereyra is near Kaka but now that Morata benched Llorente and Pereyra will get more AM time, Pirlo will have three fast players in front of him to do that again.
With Vidal as AM and Llorente as CF the only player who could run to catch Pirlo's passes was Tevez, now will be different.