The Russians didn't win the war in Europe, the Americans did. Why?
The Germans vs the rest was the start, but in 1945 it wad the USA vs the Russians (aka the race for Berlin). The question being, could the Russians have kept going through the Allies to the Channel?
Fact, the Russians knew the USA had the bomb, but would they use it? In the short period after Trinity they invade the Kuril Islands and were sweeping south, after Hiroshima they stopped - now they knew the USA would use them and their conventional superiority in Europe meant nothing.