Rome is looking better with De Rossi as a coach and they are clearly on a upgrading path, but if you ask me i dont really trust on them, they ahve very bad games were they can make anything as planed.
Maybe they can beat Milan but nothing more after that.
If you watch Milan last game, you will know that Rome will not have their way to beat Milan because they have defenders that will hodl that defense strong until they achieve their goal in this season and, their coach still have more skills to impact to his players to continue performing through out the season.
I know that game can change at anytime but it will be difficult for this game to change for the favour of Rome because I know it will not be easy for Rome strikers to make their coach happy in this game and the Rome players will know that they meet strong team.
Actually, for the first leg I feel that if Roma feel unable to beat Milan at the San Siro then they just need to hold Milan to a draw and Roma just have to try to win in the second leg when they are the hosts. Arsenal is a difficult opponent who has even had a higher level of consistency than Roma this season. So even if Roma loses in this match, I feel that it is normal and De Rossi will not be blamed at all. Because Milan is indeed a strong enemy who is currently ranked 2nd in Serie A. It's just that if Roma manages to win then De Rossi's name will really get more attention. And his reputation will increase greatly.