What if German armies went around the Russian cities?

[2020hindsight]

The main problem behind the strategy for Barbarossa was that Hitler could not decide what was the priority target and instead chose 3 or 4, depending on how you count them. He wanted to take out Leningrad and Moscow and grab the grain and the oil fields. A four-way split reduced the concentration of sources that is the key to success. Probably his best choice would have been to go for Leningrad (with Finnish help) and Moscow. The Ukraine and Baku could follow. Leningrad ended up as a siege anyway. Had Hitler taken Moscow quickly, it would have been a major political blow to Stalin, plus a loss of communications ability and industrial capacity. If he wanted a third striking force, then go for the Ukraine to take out Kiev and the Donbas. The Volga and the Caucasus were a prime case of overreach.