I think this is all down to Allegri not being particularly fond of Dybala.
Before Allegri left us the last time, you could already see how Dybala was frequently being left out of the starting 11. It probably had something to do with Allegri leaving. The board wanted Sarri to get more from Dybala. Fast forward to today, things haven't quite worked out. They must be evaluating if having Dybala on 12m + bonuses is worth it. And I think Allegri would be happy to reinvent the squad without Dybala.
I love this boy just as much as the next fan. But there's no denying that if Allegri had the opportunity to choose between Dybala and Tevez, there would only one winner.