No need to be sarcastic. The problem of Soviets isn't so much a single unit but the combination of good units overall, which leaves Soviets with no disadvantage.
It comes down to the question of what makes a good faction? I would say the following aspects (I marked every aspect for the Soviets with school grades (A - F):
1. Cheap units
a) Upfront unit cost (Soviet units are amongst the cheapest in the game) A
b) Reinforcement cost (Soviet infantry is amongst the cheapest to reinforce, Elite inf is a bit more expensive) B
c) Do Upgrades have to be researched? (This is actually a weakness since Molotovs and AT-Nades have to be researched) D
2. Firepower
a) DPS (Soviet infantry maintains a decent DPS) C
b) Wipe potential (Best wiping potential in the game due to big and cheap guns, 120mm mortar, Zis barrage, good mines, T-34/85, KV 8, ISU 152, smaller Axis Squads) A
c) Range (two 60 range TDs, Soviets are good here) A
d) Artillery options (Best artillery options in the game, 152mm, 120mm mortar, B4, Kat) A
e) Flexibility of their units (the abilites are good on some units like the ZIS and bad on others like the T-34 capping ability) C
3. Durability
a) Large squad sices (Soviets have the largest squads and the largest weapon crews) A
b) High HP and armour on vehicles (Again, excellent grades for Soviets, KV1s that can take more hits than Panthers, a great performing IS-2 and of course KV-8s that can dominate Paks even midgame). A
Now where exactly is Soviets weakness? They EXCEL at cost, firepower and durability of their units.
You are overselling some of the points. Like, how do the Soviets have A for wiping potential when they have horrible on the move DPS units and no grenades? Soviets wiping potential comes purely from the T70 and from late game units, and they are worse at wiping squads than the USF units are.
And durability gets an A, eventhough the toughest stock tank is a T34/76 that has barely any armor, no blitz and no smoke.
There are also catagories that you have not mentioned in your list, like infantry based AT options(worst of all factions), forward retreat options (worst of all factions), on the field healing and reinforcement options (worst of all factions). Fortification options (not great).
Now, I don't think Soviets are weak by any strech, but they are not this complete faction with no weaknesses that sticks out above all other factions either.