They are very good, but very little pressure put on them the last season. Three teams who could hurt them; Chelsea, Liverpool and United; should have made life harder for them the first time they played. Liverpool imploded after Mane's red and we were tame in our approach to the game. Chelsea had their own shit going on last season. If we had won our game, the gap would have reduced to only 5 points after match day 16 and would have had us in the running. There is very little chance to recover when you allow a team 11 points lead that early on in the season. Teams only buckle when the chasing pack maintains a constant threat and puts them under pressure.
This season the chasing pack, which I am assuming will be those three teams again, need to do better than they did last time. They won't run away like they did last time if they don't give them 3 easy points. I think it'll happen too. No way they are going to score 100 points again.
Don't think a lot of teams have figured out how to play against them tbh. If you sit back and defend deep they're bound to score sooner or later. If you attack them, you're leaving your defense exposed and they'll rip you apart with their pace and deadly strikers.
The only way seems to be to take all your chances and hope your defense holds up.
For the smaller teams there is only one way to play against them, i.e. to put 10 men behind the ball and hope to nick the game on an off chance. Those teams are not going to match by going toe to toe against them. The only struggles I remember Pep's Barca and Barca faced were then they played against a team who were extremely compact in defense and were ready to deny them any space.
Top teams like Liverpool, United and Spurs should look to exploit their vulnerability on the counter. A team that plays that high a line is extremely susceptible on the counter if done right. There is no other way to overcome a Pep team; you are not going to beat them at their own game. Poch tried it and came out looking extremely naive doing it.