we used to have 3 walls to block a counter, the front line with the initial press, then Fern sweeping in on the first ball out to either foul or win it back, and then the back 4 if it got that far, but there was often enough disruption in the first 2 phases that it was rare we got badly exploited.
Now we have 1, the back 4, we have no midfield in the defensive transition so in effect we have 30/40 yards of blank space for the opposition to create a counter in and therefore they get much clearer opportunities and the defence now gets caught between ideas of how to stop it hence we get a plethora of individual errors as they aren't singing from the same sheet and are put under too much critical pressure, instead of being there (like say at Liverpool) to just clean up and been the final wall to an already disrupted counter.
That's why Liverpool have crushed the league and done us over, because the midfield is just there to crush any counter and win the ball back, so the backline rarely comes under critical pressure. What Pep has failed to acknowledge in purchasing Rodri was the unique factor that allowed his style to work in 17/18 and 18/19 was the energy of Fern allied with his technical skill, to allow us to play Pep's way in attack but have the legs to have a 2nd wall to counter attacks. Gundogan was a drop-off but given the sweeper role with a really intense, Bernardo inspired first press, his job was more to pick up the loose counter and recycle than break it up. Last season both he and Rodri were tasked with breaking it up a lot more and it failed miserably.
It's why Gundogan, Rodri and the likes of Mahrez might be good players but they don't suit what Pep needs in England. The unfortunate thing is it's been completely missed and we've unravelled what works and created something that is deeply problematic for a Pep style of play.
Equally, we had a plethora of simple chances in tight games last season that we squandered, largely Jesus and Sterling, that puts us on the back foot. The low block isn't the killer because we still get really good chances in pretty much every game, it's not taking them when they arise and instead having to wait for 6/8 attempts before our front men score. Liverpool tend to take their early chances, as we did in 17/18 and 18/19 and it sets the tone for entire games.
We can't do a 3 phase press with this current squad so Pep has to either philosophy or make a couple of signings to address it in the next few days.