What De Rossi is getting now has never been get by Mourinho before, even though Mourinho previously managed to win the conference league for the first time for Roma, he was still considered incompetent in coaching Roma, in fact he was fired when the league was still running for half a season, currently, De Rossi has full trust from Roma to continue building the squad he has by budgeting a lot of money to buy new players, but this is different from Mourinho, who at that time asked for a small budget from Roma, and he was only given the option to strengthen the squad with loan players and clearly that created a conflict between Mourinho and the owner of Roma who ultimately fired Mourinho as coach.
Compare results achieved by Mourinho and De Rossi, it's unfair to sack Mourinho and hired De Rossi then end the last season with worse result than with Mourinho in two season ago. In money spent for transfers, it's more unfair between Mourinho and De Rossi.
I really don't know what's happening in Roma recent months and why they decided to take risk and spend too much money for transfers like this. In the last months of past season, there was rumor that they considered to sell their captain player for finance improvement. Now, in this summer, things changed considerably and they did not sell players to get money but actually have net positive transfers with many big transfers.
De Rossi ability to build Roma squad last season was quite good, but we have to admit that the bigger role in forming the squad actually belonged to Mourinho, because after all, De Rossi only continued the work left by Mourinho with a complete squad, but to next season we will see what happens what De Rossi can do with the Roma squad that he will 100% build..!
De Rossi did his job well but it's not true to say his coach results are better than what Mourinho did for Roma in two previous seasons. He already was given chance to work longer with Roma and he will have many more pressure in a new season after the club decided to spend considerable transfer money in this summer.