Looking back at the game with a cooler head - Pep got one over on Arteta.
We were the best team for most of the first half, when we were moving the ball quickly and getting people forward. Pep realised that Kepa wasn't anywhere near as good as Raya at playing long balls out and so put a very high line of 4 right up the field to limit his options. His quality of ball was such that it kept coming straight back at us. He also realised that Gyokeres can't hold the ball up for toffee, so made sure he wasn't given the space to be an outlet.
That completely nullified us, and Arteta didn't make changes to prevent it early enough.
Hopefully with Raya and other options (Ødegaard, Eze) to have a bit more push in the midfield, we'll be able to do them in the league.