Remember when Klopp and Conte had no European football mid week so they could do proper coaching and not worry about playing every 3 days. And Klopp got Liverpool and back into the CL and Conte won the league.
You know why Mourinho generally doesn't take jobs mid season (He needed the Spurs job to rebuild his brand, plus he loves living in London, too good of an opportunity to turn down.) because he needs those 5-6 weeks of pre season to implement his ideas properly because there is no other time in the season he can spend quality time with the squad. Or like how Klopp was suppose to take a year sabbatical off from management/coaching as he has a set way of doing things. But the opportunity to manage Liverpool was too good to turn down.
Now a first time manager who comes in thru the season, then after 3 months into the job, a global pandemic happens and shuts everything down for a few months. The players have to train in 1's and 2's and have discussion over zoom. At best they have maybe 3 weeks together before the restart. Form picks up, gets to a final. Usually a the team gets 4-5 weeks off before pre season. The squad gets 4 weeks off before its next game and pre season is really a week at best. Now the season starts you've had less time off than everyone else and you go into a season playing every 3-4 days with international travel. Literally no time to work on the training ground and a lot of those days inbetween games are recovery.
Has Action Man Hair, made mistakes yes. But let's not act like he's been working under normal circumstances either. Sure you can say but everyone else is in the same position. Well they aren't really because it isnt most managers first job nor have they ever had such limited coaching time with their players in there first job. Yeah he might just be out of his depth, but let's not act he's had it easy either. You can point to the transfer business, him falling out with players etc. But the thing that Arteta is suppose to excel in, he truly hasn't been given the time to do it.
Between the time he was appointed and the end of the season just gone. I've seen enough to see that there is a decent to good coach.