You're making up those percentages out of air.
Yes I am but that is how it really is.
Sure, Tim has a ton of system design experience being (among other things) one of the co-creators of SPECIAL we all know and love. Anyone who denies that has no clue. Therefore he probably was there for Josh as a senior consultant and a walking encyclopedia of knowledge. But he mainly did programming while JES had near-total or total freedom in doing core systems. Had Tim done system design , believe me, Pillars' mechanics would have much more sense. (And I'm not taking a dump on Sawyer, I may or may not like his approach, but it is evident that he had his hands more than full)
Look everyone can have a say. Developers are people, they work together, talk to each other, eat together, spend time together. Tim, Boby or person X may have influenced some design decisions with their good ideas or good advice. But If everyone did everything this wouldn't be half the game it is. That is not how these companies work. Everyone has his or hers sphere. That being said, JES had the last word on system design. Core systems were JES' job as the design lead, not Cain's or Boby's. Pillars of Eternity was his Trial of Iron, so to speak. Bobby Null as far as I'm aware was the level lead on Pillars and did fine. Od Nua (Mega-dungeon) was his idea and that's great.