Again, apart from the SU-76 NOTHING on your List really underperforms. The 34/76 can arrive very early and take your enemy by surprise and you can build them in swarms and overrun your enemy. SU-85 does its job really well and the T70 fucks shit up left and right. Also you didnt even mention the Katyusha also a Soviet stock unit that does really well.
The thing is that the T34/76 DOES underperform. Don't think of the tank itself, think of it in the context of soviet teching. If you go for T3, it is the heaviest tank you will get for the rest of the game. That is not a vehicle that you can really expect to win off of unless you have most of the map for the rest of the game, as you WILL lose some. In terms of armor swarming, it costs 310mp and 100fu, which is 40mp and 25fu less than a P4. That means that for every 4 P4s, you get a T34/76. That is not a numerical advantage worth having, since the P4 is not only a better tank to begin with, but it also scales better (armor bonus at vet 2, blitz). Not to mention that the price to tech to a P4 and the price to tech to a T34/76 is the same I believe.
The T70, as I stated before, is fine.
The SU85 is a good unit. I agree. It can counter medium armor very well. However, remember that we are looking at soviets in terms of lategame potential. If the Soviet player has su85s, and the axis player has a KT + panther or just 2 panthers, the Soviet player will be hard pressed to hold the line. Not only that, but the SU85s cannot chase, so killing armor is just about out of the question. \ But remember that going T4 means that you do not have access to a frontline AI unit. And if we are looking at soviets without callin meta doctrines, that means that you do not have a hard counter to lategame german infantry, such as Pfus, obers, falls, and lmg grens. Relying on conscripts won't do you any good, the only real way to have a chance is to have gone a penal heavy opening and gotten some vetted penals out, or to have good RNG with indirect fire. The SU85 should at least be able to hit targets, its accuracy is not good enough IMO. Not to mention that your entire lategame tier structure gets countered if your enemy gets a JT/ELE/Pak43.
I did not mention the Katyusha or the M5 halftrack because I am talking abut front line units that you will be structuring your army around. The katyusha is a good unit, but you cannot expect your frontline to stay together if you focus on building them. You need to put fuel towards units such as SU85s to protect your units. The M5 is in a similar boat. It is a good unit, but comes a little late, and is a support unit. It won't be killing units, and all it does is keep your conscripts/ support teams on the front line, since its AA upgrade is quite useless.
So please, tell me how the current soviet tech system is any good lategame? Both German factions have access to highly armored units (KT panther sturmpanzer) which allow them to survive in the lategame with their stock army. USF has the synergy between the M36 and that Sherman being in the same tier to make up for their weaknesses. WHat do soviets have?