With no Arsenal matches to keep me busy, I have succumbed to my morbid curiosity and decided to wade into the murky realm of people that are anti-Mikel Arteta to try and understand where they are coming from.
I do this because I 1) don't want to have an echo chamber of ideas that I am looking and thinking about 2) I have had Arteta skepticism but struggle to see where you can not have seen the last 9 months and not be the least bit optimistic about where things are going.
My basic understanding and I am trying to be as reflective of what I have seen in my discussions is that there were several decision points in the past that they think Arsenal made the wrong choice. I will go through them here.
Hiring Arteta was wrong to start with, he wasn't proven, and taking a shot on him over a "proven" manager was wrong. I don't think that thinking this is wrong, I disagree, Arsenal almost did this before backtracking and going with the proven guy in Unai Emery, that didn't exactly work out either and this was certainly a risk.
Arteta should have been fired after the 2020-21 season. This really seems like the big one for people and what they point to as the problem (ignoring new evidence). Arteta failed to improve on the previous season's 8th place and failed to meet what was the board's expectations that they communicated in December of that year.
This is my interpretation because there haven't been the same specific goals so things have to be read between the lines, I think there was a realization that the actual talent level of the team was not where they thought it was and that the actual timeline of goals was re-evaluated with a new round of investment in the first eleven over the last two summers.
I don't think it would have been wrong to make the choice to fire Arteta at that point, I was highly skeptical at that time as well but that wasn't the decision made so it really doesn't help to dwell on what didn't happen.
The next point was the first half of the 2021-22 season where Arteta should have been fired in December 2021. This is again to something that would have been justifiable. The first half of 2020-21 was bad before the "Since Boxing Day" stuff came up with Arsenal playing pretty well (and probably saved his job). The first half of 2021-22 wasn't quite as bad but still had Arsenal not playing well and I was very much ready to move on (not necessarily right then because there wasn't an obvious candidate waiting to take over) from Arteta.
What happened instead was that he improbably turned things around and the team played really well. There had been fits and starts of a team that was implementing what he wanted to do and then it seemed to click with Arsenal playing like a top 4 or better team.
This improvement is acknowledged but minimized by saying that this is in spite of Arteta and not because of anything that he has done. Basically that a competent manager would have already reached this level and any average manager would be challenging for a title with Arsenal right now (no joke I was told this).
My takeaway from this is that under Arteta Arsenal haven't made progress, even though basically every measure of performance shows an upward trend. Arsenal haven't shown ambition (because they have kept him) even though they have invested quite a lot of money in the squad to increase the talent level. Arsenal are doomed to midtable as long as Arteta is here, even though they are currently in first place (not that I think they'll stay here) and well positioned for a return to the Champions League.
The TL;DR is that I think Arteta Out people are stuck relitigating the past, they have made the opinion that Arteta is the problem a key part of their online identity and accepting that the current evidence might suggest otherwise is something to ignore. In the long term, eventually, almost all coaches fail so they will finally get to see what they want but there isn't a lot of substance to the case that there is a pressing need to replace Arteta.