Arsenal is not even in a good situation in Premier League and that's why I think we can't expect them to have good results in the tournament like Champions Legue.
Arteta is getting more experiacned and he id making progress but he is still far from a coach like Ancelotti with lots of experience in Chmapinos Leeague and tthat's why I think Real Madrid will have much more chance than other teams.
Domestic performance never been had any impact on UEFA performance because these both are completely different things and many teams done good job with they had never been good spot into domestic league, so Arsenal is still one of the top teams into Champions League with I have feeling they can go through until last four then we have much better sides which can bring them down with their own quality and performance with Arsenal still needs more time and experience for having better results in top games which are never been easy for any club which is having squad like them. Mikel Arteta is surely one of the best young managers which is taking good experience and lessons after their every defeat and trying to improve their performance and fixing holes which are hurting them with he is not comparable with Carlo Ancelotti which is currently one of the best in business.