You're right, Chelsea were too comfortable, they got carried away by the 2-0 win, if they had defended properly and tried to add more goals I believe they would had won the game, to be honest the 2 1st half goal really killed the morale of Arsenal players but Chelsea gave them a better opportunity to score one and it lifted their team spirit that was why they were able to get a comeback draw.
Pouchettino is really doing a good job currently but I think Chelsea's defense needs more strengthing, they should try strengthen their defense line by the January window, well the both teams put up a show yesterday and made the match so interesting, it was the toughest match of the week, Arsenal were lucky to get a draw they were the favorites but didn't quite impressed in the 1st half and conceded 2 goals well it's a London Derby so things like that are always expected.
A little analysis from me. Chelsea's mistake against Arsenal was that they were too confident that they had won against Arsenal from the 60th minute. Even though Arsenal were hotter this season when Arteta replaced players in the second half, and that is Arsenal's strength this season.
And Arsenal's mistake, they always have difficulty against teams that play defensively. Apart from Partey not playing, from the start Jorginho played, Arsenal were unable to create any attack creation at all. This means that Arteta still likes to make mistakes in making line ups for matches. Gabriel Jesus, in my opinion, is finished. Ode without Partey, just a midfielder like Newcastle's Guimaraes.
Advice for Poch, don't be careless in changing players, even the tempo of the game.
Advice for Arteta, play the best players, not the existing players.