Obviously they didn't plan on getting Pep when they signed Silva and Aguero, no need to point that out. I just named them to show that the foundation was already there.
Thing is, they didn't sign Beigiristan back in 2012 for nothing. They decided to make Pep's Barca their role model and year by year they became more like them. Of course they didn't bet anything on him signing for them sooner or later but they developed in that direction regardless, and if Pep hadn't gone there they would've employed a coach with asimilar philosophy. Like it or not but the current City is the best example on successful long term planning in football there is. There are many top squads in the world, some are 'Pep teams' and some are not. City was always one of those teams you'd say 'imagine this team was coached by Guardiola' about. Bayern even more so back then. That's the reason Guardiola had to adjust relatively little when he arrived. I mean, imagine him hitting up at United, he'd probably demand a completely new squad and only kept Mata, Sanchez and Martial.
He changed his GK twice, complete new defense, B.Silva, signed Jesus to replace Aguero which didnt work out. That's more than half of the team. KdB, Silva were attacking mids but somehow he made it work as midfield 3.
It's far from easy sailing, since he is arguably the best at what he does, he made it work. Of course they wanted Pep from long back and signed Barca directors but everything about playing style, players is just myth.
Before Pep they didn't employ someone with similar philosophy, they had Pellegrini whose team averaged less than 50% possession in Europe and never topped possession charts once. They were attacking team but far from how they play today. Before that they had Mancini who had completely different philosophy.
No, they were not one of "imagine if Pep managed this team" type of team. They had fecking Joe Hart as GK, Zabaleta/Sanga, Clichy as FBs, washed up Demi and Kompany as CBs who were exposed any time they played high line.
Yaya was their first choice midfielder. No one even though Fernandinho would step up the way he did and they had Jesus Navas as one of their winger.
He more or less ripped the team and changed few players and improved few. They had oldest or second oldest squad in the league when Pep took over. So many articles on how they needed rebuild.