From the recently posted WoT Website – Update 1.20.1: Crew Improvements: “the major qualification level now affects almost all perks (excluding Brothers in Arms). The higher it is, the stronger the perk effect.”

Does this mean that a tank crew trained to less that 100% on their tank is not reaping the full benefits of a skill or perk?

If so, this sounds like a double penalty to a skill/perk – one for the skill/perk not being at 100% and one for the crew skill not being at 100%. And if so, this is not explained in anything that I have seen published by WoT (until now).

Likewise, this dynamic makes premium tanks a bit more valuable than before.