Really appreciating that the player's are having a better understanding of Pep's ideas, and Pep himself changing tweaking the formation a little bit for more defensive balance when playing out from the back.
Pep opted to go 4-2-3-1, as opposed to 4-1-4-1, what this did is recognized a distinct 6-defenders behind 4-attackers when playing out from the back versus 5-defenders behind 5-attackers.
When we played 4-1-4-1 and we play out from the back, often the holding mid would drop (the CBs would go wide) and the fullbacks tucked. This created a 3-2-4-1, from which the two fullbacks were tasked with receiving the ball from the CBs. The problem with this is that high-energy press teams have gotten really good, and if a team like Liverpool nicked the ball while playing out from the back, the spaces left open were easy for them to exploit. The other option was the team would play out as a 2-3-4-1 like Barcelona, but this was also not successful for the same reason.
4-2-3-1 allowed City to play out as a 3-3-3-1, wherein in this game for example, Clichy could drop as a LB/LCB and join Kompany and Otamendi, leaving Toure, Dinho and Navas in the middle. This was much more stable, because if Southampton nicked the ball the 3-3 formation had no gaps to exploit immediately. Another way this formation arose was instead of Clichy dropping back (Navas never dropped back btw due to his pace), Fernandinho could drop back into RB/RCB leaving Clichy, Toure and Navas in the middle. This flexibility in playing out was very useful and often confused Southampton's markers when pressuring City (especially in the 2nd half) because Clichy and Dinho would rotated as CBs.
Lastly, this also made Kevin far more useful as a wide-playmaker in the RM position. In the 3-2-4-1 Pep tried to play Kevin out wide, but the weakness in the wings (as in there was no wing) meant we required fast wingers like Sane and Sterling. In the 3-3-3-1 Kevin's lack of pace was not as much of an issue as he had plenty of defensive cover if he messed up.
Now clearly you can rotate between 4-2-3-1 and 4-1-4-1 very easily (with a shift in the midfield triangle) and for times City did this as well, but I was amazed how well the player's were adapting to the system, defensively we were very good in this more stable set up, and had a few players been more consistent, we could have won 5 or 6 nil.