Without Pep Guardiola, Busquets and Pedro would have stayed in Segunda. The reason they slotted into Pep's system was because they had one whole year training under Pep when he took over Barcelona B. They were not some great youth systems talents that were coming through. If I remember correctly, Busquets himself admitted he wouldn't have made it at top level without Pep Guardiola. As for Messi, you can say he would have been world class without Pep, perhaps, but he would be nowhere near the level he played at. Once again, all you need to do is look at his past before and after Pep. Before Pep Guardiola came and basically coerced him to change his diet, Messi was injured regularly and could literally not play a full season uninjured. He was always having muscular issues.
Guess the player that had the same issue, Aguero. And look what happened to his career. Aguero had to get advice from Messi because of how bad his injury problems became, but unfortunately for him, it came far too late in his career. That is a direct result of Pep. The numbers you saw would most likely never have happened. Xavi was going to leave without Pep as well. Xavi even said that he was off till Pep Guardiola convinced him to stay.
So throw all that together, and add to the fact that Pep Guardiola was the main reason that the way football was viewed by the general public changed after 2008.