Disagree with it being "only" Arteta. Partey dropped a terrible game, and Trossard, and several other players were simply mediocre. And Paul, who doesn't deserve the Tierney name, all but rigged tons of fouls
Arteta's system doesn't benefit either Partey or Trossard. They are out of position. Having a comfortable role and partnership is key between coupled positions like RB and RW. If they were in their traditional roles, we wouldn't be dropping 2 points to Fulham.
Trossard has played good at ST before multiple times — I know I'm not the only one who wanted him to stay in that spot when Jesus came back from injury last season. Dropped the worst performance I've seen him do in an Arsenal shirt today.
Partey is mainly Arteta's fault though, but he could do way better even so.