A very high percentage of managers fail anyway, and Arteta hasn’t been manager anywhere else, he had no pedigree at this level. You don’t get any spidey sense points for that “prediction”.
Overall he’s done pretty well. He’s made us into genuine contenders. We are the only side to have even challenged City for the last 2 seasons and last year we pushed them to the last day. We got 89 points, our second best in the PL, only one point off The Invincibles. Arteta hasn’t been the abject failure you presumably predicted.
That said, it seems increasingly clear that Arteta isn’t going to get us over the line. I bear him no ill will, but we do need to move on from him. Although I agree we probably won’t.