If Tottenham are going to win their last game, Arteta will end up finishing behind them the third time in a row. It is crazy to argue, that Arsenal's expectations should be lower than that of their London rival. Tottenham sacked two managers during this time, their best player threw a tantrum for a while and generally the post-Poch era hasn't been brilliant for them. Yet still better than Arsenal.
The placing also doesn't tell the whole story. In general their football is boring and uninspiring. There are plenty of teams in the EPL that have worse players, that are far better organized and play far better football. Its not like Conte's Tottenham is particularly brilliant, but you could see the immediate impact he had. Just like with Tuchel previously or the likes of Pep/Klopp before that. The same is also true for Howe/Newcastle. Of course the latter invested a shitload of money during the winter break, but their performances are night and day and they certainly shouldn't play Arsenal off the park. Good manager make a difference. Arteta has shown almost nothing so far. For all the talk about building something, they are still not more than the sum of its parts. His recruitment has been questionable, his tactics are bland and his handling of players has been horrible.
The only thing he can point to is, that he worked for Pep.