Manchester City and Real Madrid always give a lot of importance to their domestic league and Champions League but we don't see that in case of Arsenal. Arsenal may take the English Premier League tournament very seriously but they are not too interested in the Champions League tournament. If they had given more importance to the Champions League tournament, their performances in the Champions League would not have been so bad on a regular basis, while in the English Premier League they are rightly second in the points table.
Arsenal are just beginning to pick form in the premier league as they weren't title contender before but for the last two seasons, they have been the only one chasing Manchester city. I think Arsenal wants to win the premier league first before they start concentrating on the champions league as it would be much easier to win the premier league than to win the championship league. The champions league has alot of heavyweight clubs that arsenal can't comfortably win. There's Real Madrid, Bayern Munich, Manchester city and Liverpool is right there above them when it comes to champions league therefore winning the premier league should be their priority first.
You're right, that's what I've noticed as well, because Arsenal isn't too focused on the Champions League they want to get the chance to win the league, and I've heard some people say Arsenal will perform well in the Champions League and win the title, but it won't be easy for a club like Arsenal to win the Champions League with those players they don't have any strong players with Champions League experience, and that is why anytime they qualify in the league they don't used to have the opportunity of winning the competition anytime they will be knockout in the round 16 or 8.
Arteta lacks the talent to coach Arsenal in the Champions League because the UCL is different from other leagues. You must focus and see how you can make information in the games because that is the main reason why many clubs do not win matches; they do not know the actual players that they can put in and win games for. If Arsenal gets the chance and wins the Premier League, I am confident they will also win the UCL. Let's see how the competition plays out next season and who gets the opportunity to win the game. Arteta does not have the talent to coach Arsenal in the Champions League because UCL is different from other leagues.