Guardiola is without a doubt one of the greatest managers of all time.
for me, there were 3 (maybe 4) revolutionary teams in football history:
1) Cruyff's Total Football Ajax/ NT. no explanation needed.
2) Sacchi's Milan. Their defensive prowess is legendary but not because of last ditch crazy effective tacklers. They defended in a way (offside traps, zonal play) that it didn't even get to the point of a tackle being necessary. Pretty much wrote the textbook for modern defensive arrangements.
3) Guardiola's Barca (08-11): Insane positional discipline, off the movement, hyper attacking fullbacks that not only played up the wings but also slotted in on midfield when necessary to restrict opponent's countering channels (RM copied us on this with marcelo/ carvajal).
You can argue for Herrera's Inter to be amongst this list too for catenaccio.
But yeah, Guardiola has his flaws and so did Sacchi and the like. But there's very few managers who can make a bunch of world class players play above world class level with their system. The reason he didn't win CL with Bayern is because of bad luck (v Atletico, they completed stomped them at the Allianz) and because some bayern players weren't challenged by their league and believed their own hype a bit too much.
even lucho before his 16-17 midfield meltdown is a tier above valverde IMO.