To tell the truth I think it is even more logical now to give Roma a chance for the title by placing a bet on them. Because if De Rossi manages to develop a solid strategy for Roma things can get much better for this team in a short time. Not only here but also in the Serie A. Maybe Roma would make use of more transfers to be better in squad quality as well but they don't have a very big transfer budget as far as I know.
But I think that the current squad is still good enough to be a serious competitor for the title.
It may happen that before the coach will be able to get all this fixed, there maybe not enough time for them to be able to get to win the Europa that's if they even make it pass the quarter finals, the players will have to start getting used to the new tactical approach that will be introduced to them by de Rossi, and that's definitely going to take some good time for them to fix, some of this players who were more used to Mourinho will definitely have some challenges getting used to de Rossi so it's obvious the odds are against them in many forms so they will most likely not win the Europa.
Even though Roma still has a chance to qualify for the round of 16, I doubt that Roma can reach the quarter-finals or semi-finals. Jose Mourinho, who has a lot of experience in the European league, has difficulty building Roma performance, let alone the current coach, but yes, the strategy that the coach has different and I hope Roma will not regret their decision to fire Jose Mourinho.