Russia would have over ran Western Europe without a doubt. Patton was a good General but sheer numbers wise he must have been drinking to think Russia would be a cake walk, at the close of the war Russia had 6 million battle hardened troops, and tens of thousands of T-42 tanks. The T-42 by itself was far superior to the Sherman...The Sherman was a pee shooter in comparison. The Russian troops themselves I would bet were superior to US troops to, considering that they experienced battles that dwarfed the Battle of the Buldge or Normandy on a weekly basis..
The Russians expended a lot of manpower and equipment fighting to berlin against an opponent that was out of supply, equipment, and filled its ranks with volkstrum. The idea the Soviets would simply run right over the Western allies is misguided. We have bought into the propaganda about the Soviet military machine. I think it was overstated at the end of the war all the way through to its collapse in 1991.
The Sherman was a pea shooter compared to German tanks. But Pattons army covered vast amounts of ground with it. The Soviet troops and their C&C were much more rigid than the US military. This caused a lot of uneeded casualties and indecision. They also had to deal with the dreaded NKVD and political comissars. Talk about killing your morale. Attack that hill, if you dont, you will be shot by a comissar. You are dead either way.