It's fair to say that Yaya has quite a high opinion of himself and that often led to clashes with Pep both at Barca and City. I think he's thrown the race card around previously during his time at City when it came to the voting on a few individual awards that he was never really recognised for despite a few ridiculous seasons.
If Pep was so bad why did Yaya stay one more year when he'd hardly used him the season before?
I mean throwing out the race card is a big accusation to make against someone when you aren't offering up any other names. It's fair to say he's not worked with many African players he had Eto, Toure & Kieta as Barca, don't think he had any at Bayern and I assume it's only Toure at City but I don't ever get the impression that way by design they're currently in the process of signing Mahrez who is African.
I mean if you are going to say other black players felt the same you are really going to have to name them because now it's just speculating on who it might be by naming every black player who he's ever coached.
Good news for Pep is it's come at a time of year where he can just let the story fizzle out he doesn't need to say anything and by the time the season comes around people/journalists will probably have forgotten about it and moved on.