And this is where everything else you wrote falls down, because Pep explicitly said that he can trust players who have played in lower divisions. He said that when his youth players in Barcelona had played in the third division, that he could use them because they've experienced losing and big crowds and high pressure, but here he couldn't just throw the kids in because they've no experience.
So, if kids can go from the third division into one of the greatest club sides of all time, the they sure as hell can come in to replace our Right Backs.
As for Maffeo, once he got into the Girona team, he played every game he was fit for, missing 2 of the last 10 (including the play-offs) because of an injury.So I do expect him to play the vast majority of the last 15.
And I'll say again, if he doesn't play for us next season as 1st or 2nd choice RB, he'll never play for us, because at that point we'll be buying 2 new young RB's to replace Zabaleta and Sagna, and he'll realise that all his paths to the first team have been cut off and leave.