Do you trust the Soviets GDP numbers? Even if you do, the Soviets were spending upwards of 40% of their GDP on the military, not exactly a quality of life enhancement. Even discounting that, the only states that I could find that might qualify are Moldova (about the same level) and Ukraine about 72%). Ukraine is pretty clearly the Russians are to blame there. Other post Soviet countries, like Turkmenistan are > 580% bigger real GDP. Uzbekistan, Armenia and Kazakhstan are around 3x bigger GDP. Belarus, Tajikistan and Azerbaijan are around 2x bigger GDP. Kyrgyzstan, Russia and Georgia are about 1.3x bigger GDP.

It doesn't really matter if I do, it matters if the economists who study it do. It's not controversial to say that "shock therapy" was a disaster, and that living standards have plummeted since the collapse of communism in many countries.