How is Mace just a figurehead? He runs shit and his kids fall in line. Everyone knows Willis is more intelligent and Garlan is a more capable warrior but for now Mace is in charge.
um this doesn't sound remotely like mace. when has he 'ran shit'? are you familiar with the 'grand tyrell conspiracy', now I don't buy all of it but I'm pretty sure Olenna is pulling the strings in that family and Mace is dancing to her tune. margaery is also shrewd as fuck.
olenna and margaery are the power players in that family.