"The Yak-9T and P-39 were used for ground attack by the VVS"
This is really a western myth. Most were deployed in the fighter role, however, just like USAAF and RAF fighters, they did strafe, ect, but that was not their primary function. They were also not used as "tank busters" despite having 37mm cannons.
The Eastern Front tended to be populated by tactical bombers and fighters, so the air combats were as a result, at much lower alts, there were no "bomber fleets" at 25k, so more of the fighting tended to be lower down, as it was in much of the Pacific War (at least untill the B-29 missions late in the war). Another difference was the air units in the East tended to be deployed much closer to the front, in primitive temporary strips, and were highly mobile.