Yeah true, I also think that the club also lacks squad depth, in the sense that, when the main players for a particular position is maybe injured for a particular period of time maybe 4 -12 weeks. In his period of absence who takes over, is the substitute player effective enough to at least fill in the boots for that period of time his away? I think that's another Arsenal problem too. If the main players get fatigued or injured do they have reserves that can perform at top levels, I guess no.
Arsenal is battling this existing problem that kills their efforts as a team, every EPL club has a loophole that's so hard to fix, take Liverpool for instance, their right back isn't proficient for a while now, and they've not fixed it. Arsenal would find it hard to resolve similar dispute in the coming season. If it'll cost the club a lot to place strong substitute for injury prone players, they could adjust the way they train and upgrade medical departments to sustain key players till end of season. Liverpool didn't experience a thing like that, Sallah played all through with lesser challenges. Arteta can adopt the method that works, and build on time.