User blog comment:WolfgangBSC/Wolfy World of Tanks/@comment-24231515-20160102011530/@comment-27820070-20160102075936

Lol 70% of WoT is RNG based. 20% goes to base stats (like the horsepower to ton ratio, ground resistance, etc.), and the other 10% would be garage related (because you don't depend on RNG to give you new tanks and such). The rest is based on whether you get the short or the long side of the stick (IMO, I always get bad RNG)