A lot of it is due to efficiency of the case itself. I don't know her personally, but I'd be willing to bet next season she's shooting a BR variant of some kind. You can shoot the same bullet to within 1-200 fps of a 6 Creed while using 32gr of powder instead of 42gr of powder.
That being said...many don't have good fundamentals in PRS, whether that's breathing, trigger pull, building a position, or following through. So a 25# 6BR with a 5-port muzzle brake is "easier" to be bad and still spot your shots. Give many of the "good" PRS shooters a 17# 308 with a suppressor and they'll struggle for sure. You don't have to look far to see top PRS shooters slapping the shit out of their 5oz trigger and still shooting a 90% hit percentage.
The admirable thing about someone like Allison Zane is she appears to be starting with solid fundamentals that are allowing her to dominate using a rifle cartridge and system that many would think is sub-optimal based on current trends.