1. Mikel Arteta needs help
Mikel Arteta should not be completely absolved of blame. His substitutions were slow and conservative, the system is a patchwork and not a long-term solution, while the manager is the leader of the time and has to be at least somewhat accountable for their individual errors. That said, the majority of the blame for this defeat lies with the players, not Arteta, and it leaves the Spaniard needing help.
Arteta can only do so much, and as he hinted at in his post-match interview, the controlled performance his team produced is a sign of the progress he is making but that it is undermined by the individual mistakes of the players. Arteta is a chef working with gone off vegetables.
On this occasion, Jose Mourinho’s defensive approach was ideal for the specific game. Looking longer-term, however, Arteta has made the greater progress with his new team, instilling an identity, system, philosophy, and culture. But he now needs the tools to compete at the highest level.
As Unai Emery before him, Arteta is hamstrung by the players he is working with. Until Arsenal provide him with a better squad, matches like this will continue to haunt them.