Huge parts of Red Army did "spontaneously disappear", i. e. were defeated piecemeal, surrounded and overcome with modest German losses, in June and early July 1941 - and, after the advance had slowed down somewhat in August, the Germans achieved a number of similar brilliant victories in September (Vyazma, Kiev...)
Suppose that most of the rest of Red Army spends end of October and November in trying to retake Moscow and defend Kuibyshev. And suffer a similar string of disastrous defeats. The rest after that does try to hold or counterattack against German vanguards here and there, but never succeeds for long.