Roma's game is still quite good. there are good players like Dybala and Lukaku in the team. Mourinho's departure didn't have too big of an impact on Roma's game. but you can be sure that Brighton will make things difficult for Roma in the next match. but if Roma can get up now, maybe Roma will become a competitor to Liverpool and Leverkusen.
However, in the group stage, we saw a bad game from Roma. and now they are rising again to try to enter the European League trophy competition.
Not only Mourinhos departure didn't do any damage, but they actually became better after he left as well. Which really isn't great for Mourinhos legacy as well, dude has been around for a long time and he still ended up being wrong in most cases, I feel like it wasn't really all that easy to handle.
I personally believe that the best thing to do in this case would be Mourinho to go to Saudi Arabia, because they would hire him just based on his name alone. De Rossi on the other hand may have a much better career after this, because he took over a team that weren't doing that well, and ended up having some great wins, and even streaks, to keep the team alive and doing well. These all matter to him, and should be important.