Meanwhile Jove and Luvnest have a 70-80 winstreak with soviets. But that's none of my business.
The reason is simple: Soviets need more micro, tactical thinking and combined arms. You have to recon and flank your enemy and keep your low health tanks and rocket artillery alive. Thats a lot to do for a player below rank 1000.
On the other side the soviets are really strong if you pull it off the right way. Soviets are good at flanking if you know how, their low health tanks are cheap and are capable of doing quite a large amount of damage for their price.
I would say Soviets are considerable stronger in comparison to axis faction on a top skill level and worse by far at lower skill levels.