Maybe "creep" is a tertiary or even lessor factor.

Maybe it contributes to a small degree to "ground condition" as in Q = A + B (where B is "ground conditions"...one characteristic of which would be "creep").

Anyway, I give whomever funded the study an A+ for being willing to re-examine previously long held "assumptions"/beliefs and being able to reject them (given supporting data). With this type of mentality, advancments could be made.

Just my 2cents worth.