It's a tough time for you guys, but it's early in the season, you have played all the top 5 teams in your first 9 matches, and you are in the relegation zone only on goal difference.
I think you played quite well yesterday before the send off, considering you play against a top team with 2 world class players who played well. It would be almost impossible for any team to contain Arsenal with 10 men when they play like they did yesterday.
I don't think you lost because of wrong tactics, formation, player selection or a lack of commitment from your players. You set up the team with 5 defenders, showing that you didn't underestimate the attacking prowess of your opponent, and yet you pressed and attacked when you had the chance. Even at 1-2 down and under heavy pressure, I thought you were still threatening on the counter, and had a chance to force a draw.
If I have regret on the decision of your coach, it is that he refused to accept that the game was lost when you were down to 10 men, and still look to chase the game with Lookman and Niasse, rather than covering up the hole left by Gana with a defensive player, and hope to equalize through set piece. More attacking players will not make you attack more if the balance is lost.
All things considered, I think the result reflects the better players that Arsenal have, and when they play well, plus the number advantage after the 68th minute, you didn't really have a chance. However, you have enough qualities in your side to recover the lost ground in the coming weeks, I have no doubt about that.