I used to play T4 a lot with soviets, but now I don't really care anymore. Soviet T4 just doesn't give you a lot of options and requires you to supplement with doctrinal tanks before you can begin aggressive armor pushes. But why be defensive until 9-11cp when you can just get T3 at 5/6 cp and be agressive with T34/76s way earlier?
Exactly this. Try to be aggressive with any T4 unit and you'll throw the game so quickly. When Katyusha was OP last week, there were so many katyusha-abusive Soviet players who were attempting to use the SU-85 and it was hilarious! I took out a couple with a simple faust + circling 222.
So your other option is to camp and get obliterated with Stuka. By the time you have enough CPs for call-ins that allow you to be a bit more aggressive, German will have enough heavy armor that the game is basically over. Plus Relic really don't want you to have BOTH T3 and T4 as soviet, so you're left with very few options.
T34/76s just provide way more utility to help your mid-game than SU-85 could ever hope to, especially now that its AT has been buffed.
SU-85 (and the whole T4 tier) needs attention.