"Just ask Napoleon, Kaiser and hitler how brainless the Russians were" - OK, let' s ask.
Napoleon would have said the best Russian generals would be those who avoided direct confrontation with his troops relying on Russian huge area, Russia must thank Barklay and Kutuzov who admitted their inferiority and followed exactly such tactics.
Kaiser would say he was very happy with Russian generals, they did not have a single success against his troops in WWI.
Hitler - he could not even imagine in 1941 that started the war against such overwhelmed Russian forces (such as 1:5 in tanks and aviation) and definitely was very much surprised how easily he destroyed all of them. Russian militarized industry, 8:1 losses and wide USA help (food and transportation) allowed them to prevail, only few of their generals (such as Rokossovsky, Vlasov) could be considered equal to Germans'.
It does not mean that Russia never had good generals, you just managed to choose very bad examples. But it was Russia 200+ years ago.