My Final Thoughts, as I don't want to dwell too much:
I feel Pep doesn't understand the balance of the squad yet, as in, who can rotate where, and when looking at the starting line up if he realizes if the balance is correct. Again, players should take massive blame, but I think the balance is an issue, for example:
You cannot play Zinchenko, Rodri, Gundogan and Bernardo together in midfield, Zinchenko is basically a midfielder in our inverted set-up.
The first 3 are mainly controllers and adept passers and don't offer enough directness going forward, while Bernardo isn't quite direct enough as Kevin or Mahrez for example, but is actually perfect in the other players roles, where he is great at controlling and passing, and occasionally finding space to be direct.
The easy fix to me would have been if Bernardo played Gundogan's role next to Rodri, now the 3 (include Zinchenko) have control with Bernardo capable of going forward. Then let Phil be the true direct #10 midfielder (which he is better at than Bernardo), and play Mahrez RW, or Sterling RW and Jesus LW.
If Pep's goal was to rest all 3 of Mahrez, Jesus and Kevin (injured), then I think that's also flawed as those 3 + Aguero have been our standout goal threats this season with over 1 g/a per 90 mins.
Also if Mendy played then that would also be a fix as it helps fix the balance a bit, but he was obviously also rested.