Gunners

Don't want to do my man Scott dirty by reposting the whole thing, so I'll summarize:

Ramsdale last season allowed 39 goals from 39.5 PSxG (post-shot xG). Raya last season allowed 41 from 50.9 PSxG, with the disclaimer that it was Brentford.

However, the big difference comes in their performance when facing easier vs harder shots.

Ramsdale performs much better than expected against more difficult shots, but either tracks or dips below average otherwise.

Raya performs poorly compared to expected against very difficult shots, but otherwise outperforms the average.

Last season, our defense was good but not perfect, and when teams attacked us, they tended to be in extremely favorable conditions. Given our defensive improvements this season, my conclusion is that Arteta is seeking to eliminate giving up the extremely difficult shots that Ramsdale is particularly good at saving (this also may contribute to Ramsdale's reputation as a "Hollywood keeper").

Therefore, what we need is not someone who will pull a worldie and make impossible saves, but someone who will steadily outperform the average against reasonable chances that Saliba and Gabriel occasionally let slip through. Hence, Raya over Ramsdale.