In order to get to the final, Roma must first beat Milan, and then the winner of the Bayer - West Ham pair (Bayer). I think the probability of this is no more than 10%. The problem for Rossi is that Mourinho has set the bar very high and even repeating it will be difficult. In general, everything can end as if there was no change of coach (if Milan knocks out Roma, and in Serie A Roma does not reach the top 4).
I am glad that at the moment the Bayer - Liverpool final is becoming more and more likely, although Bayer has a more difficult path.
They can beat Leverkusen again but beating AC Milan look to be impossible for Roma and De Rossi. AC Milan and AS Roma understand each other very well because they are both from Italy and playing against each other many times in Serie A. Roma historically don't have good head to head stats against AC Milan and it is not good signal for them before two quarter final matches with Milan in Europa League.
Playing against Leverkusen that is from Germany and Bundesliga can be easier for Roma if we exclude a fact that Leverkusen are stronger than themselves last season. Roma will have to pass through AC Milan before playing with Leverkusen and the first condition is very hard for them.
In terms of meeting record, AS Roma doesn't have a good meeting record in the last few seasons when facing AC Milan, but that doesn't mean they won't be able to beat Ac Milan. If you say they can beat Leverkusen, why do you say something different, you even say it's impossible for them to beat Ac Milan? because after all, this match has not yet been played and when it is like that, the opportunity for AS Roma is still quite open, although I also agree in saying that their opportunity is not bigger than AS Roma.
When they were still under the direction of Jose Mourinho, they were able to reach the final match, even though in the end they lost. However, I also saw that last season they were also quite lucky or in other words their game was normal but they faced opponents who were not as lucky as them. I say this does not mean I am denigrating Jose Mourinho, but we can see for ourselves how they played when they made it to the final last season.
De Rossi will do his best, because he also definitely wants to show that he is capable of bringing AS Roma to a good performance.