Delph wouldn't be playing if Mendy wasn't injured, KDB, Silva and Aguero are amongst the best players in the league, not to add he's still looking to actively replace Aguero - not to add if GBJ wasn't in terrible form he'd be first choice as he's shown. Stones would be playing if he wasn't injured.
That's essentially 6 players in the first eleven he signed. Walker, Mendy, Stones, Ederson, Sane, GBJ. That's not even taking into consideration Sanchez who will be joining, Silva who will take over from David when the time is right. He's looking to actively replace the best striker the Prem has seen in a long time, simply because he doesn't suit his tactics - if that's not enough proof for my point, I don't know what is.
As I said - if it's simply a matter of coaching, why'd he have to replace so many attackers in his time? To suggest it can be taught from a younger age is a different issue entirely, even still that still requires the technical ability and secondly, to suggest it can be coached from a young age, to then turn your nose up at grown, established players not playing that style, clearly past that opportunity makes no sense.
Pep's teams require very specific players with very specific attributes, to suggest that it's purely a matter of coaching, completely disregarding the required ability is odd. If so, Pep wouldn't regularly be one of the highest spending coaches, if not the highest spending coach at every team he goes to.