There's no question that Russia was the primary battlefield on which Nazi Germany was destroyed.
The question, though, is whether the Soviets would have done better and suffered less massive death and destruction if they had had different leadership other than Stalin. That is unknown and unknowable. Had Stalin not killed the military elite, would Russia's military have functioned better? America's most impressive generals were not in command at the outset of the war.
It is difficult to say.
Surprisingly few American generals were cashiered during WW2. Lloyd Fredendahl was replaced as II Corps commander by Patton, but that's about it. Terry Allen was relieved as commander of the 1st Infantry Division, but he was given another division to train & command so that was kind of a sideways move.
You mean if Stalin hadn't butchered all the brains in the military, destroyed the preset partisan warfare cadres set in all frontier villages, and ignored all the warnings that the Germans were coming?