Pressing last season worked great, attackers put in a massive season, and his system was still shite defensively, allowing defensive teams like Inter and Atlatico to score 7 in 2 games in Barcelona.
His system is not sustainable. What he wants is unrealistic and unpractical.
Just forgetting the little thing, that this "unrealistic, unpractical and unsustainable" system brought us a demestic treble, 4 clasico trashings in a row and 2 minutes away from the CL final with a squad, many prophesied will struggle to reach top4 and compete in the EL. Not to mention a player like Rapha looked like a Ballon D'Or candidate, who also many fans called a failure transfer.
Always nice to pick things you don't like without looking at a bigger picture, that we were with PSG the most entertaining, sucessful and best team to watch over the entire season. That's not an opinion, thats a hard fact.
You're and many others who write like that just talk out of their ass. Fact is, this system needs specific requirements as any other needs. Flick chose this, our board chose him for this, so the work is now to make these requirements work again like last season. Nothing more to say for it.
PS: I said it a couple of times already. A physical state and problems can't be solved over 2 weeks like a tactical problem. This needs a longer period of time and people need to be patient.
Unrealistic is not the system, but the fans who are not patient and demand always successful brilliant football, especially from a team full of teenagers, that is under harsh financial restrictions since years, expecting never to have a bad form.
Unrealistic is expecting from an 18 year old Cubarsi to play like the best CBs in the world without ever having a bad form, completely ignoring that Barca's greatest in history were b-players or bench warmers at 18 years of age and started to play regulary 20+. These are unrealistic examples.