I think we underrate how much disadvantage a team is in when they go a man down. The worst part is they got the red card when they were not leading and in the 30th minute. It would be a shame for Bournemouth to lose to Arsenal in their stadium when they had more players on the field for at least 60 minutes. The least that could have happened is a draw and that would have been possible if Arsenal were losing before going a man down.
Actually, I blame Artete for this. The kind pf players he's been buying recently and good players, but not players to strengthen the team in the grand scheme. He has been focused on heavily built defensive players and he left positions like the attacking midfield and wing that are occupied by both Saka and Odegaard without any replacement.
Against Bounaermounth he started a team of 4 CBs in defense and 3 DMs. A team like that will definitely struggle. I also don't think Arsenal will win the league, in fact, they won't be as good as they were last season.