Arsenal had consistency performance in last two season but keep can't reach the higher round in Champion League after this season eliminating from quarter final round.
Arsenal performed well in domestic league keep pressure Manchester City until the last matchday before winning Premier League trophies in Champion League they can't performed well as consistency in domestic league.
Arsenal seems lack winning mentality on many crucial matches when facing top teams, I doubt next season their perform well in Champion League if the knock out round or quarter final round have to face top teams such as Bayern Munich or possibility have to face Real Madrid. Arteta need improving his teams with winning mentality against the top teams and Arsenal is the only of big four Premier League teams never winning Champion League trophy.
In my opinion, it is natural that they are not fully ready when faced with the Champions League, because in fact they are just starting to build consistent team performance and it cannot be said that they are fully ready to be in the Champions League. Their mentality also still needs to be sharpened, because they are also full of young players and they definitely need time to grow their mentality to be even better, but I am sure that if Arteta can consistently build this team, then they will become an even better team and it is not impossible that next season they will be able to provide a very big surprise in the Champions League.
I believe in what is called a process and I see them carrying out that process under Arteta's direction. In the last few seasons, we can see their development is much better than the previous seasons. In terms of consistency, they are slowly having quite good consistency, so I think that is a very good thing for them to show. As long as they can continue like this and improve further, then I'm sure they will be able to do a lot.