Arsenal are in good shape but they also know their limits this season. You're correct, Mikel Arteta should tend to concentrate on EPL other than distracting the team in UCL race. Gunners is yet to face any big team in UCL this season, they meets and records thrilling victory against these average teams. EPL race would become easier and possible for them to win and not elite competitions were there's presence of tough competitive clubs. Winning UEFA Champions League is an impossible task for the Gunners, after been absent in the elite competition for long term.
Maybe this season Mikel Arteta will make a difference to last season where Mikel Arteta will also concentrate on the Champions League apart from continuing to concentrate on the EPL. Although in general I am not sure that Arsenal will progress smoothly to the next round, but for the round of 16 I am still quite confident that Arsenal has a better chance of qualifying. Because in group B there are no big, stronger teams, so it is more possible for Arsenal to qualify for the next round of the Champions League.
I hope so but im not willing to put big expectation for this club. Look at how arsenal become bottle club at the end of last season. That's enough to prove that if arsenal is always having a problem on its consistentcy.
I would like to mention an article
https://www.goal.com/en/lists/arsenal-incredible-season-losing-man-city-premier-league-title-doesnt-change/This article discussed about how good the performance from arsenal during the previous season but it must be trophyless due to the inconsistentcy by missing a few points at the end of season. I think that the most important thing to build the winning mentality for the club.
Arsenal never had this. That's also the reason why arsenal was always able leading the premier league without winning the trophy.
It's a real challenge for arteta this season but my feeling said that if arsenal may be struggling at the middle till end of season.