Ehm, you got me wrong. Let's make a quick review of the commander to spot the issue (spoiler: it is AI partisans and low ability synergy)
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As a result, we have commander, where you have some good abilities, which are not working well together, and Partisans, which are taking two slots and only one of them can be definetly called as usable one. For me the good way to go is merge partisans together into one unit, replace interception and do something with spy network.
Well you brought up a number of issues:
Mark Target is a great ability so it should not be available to commander that already have powerful tools like the T-35/85 and ISU-152.
That would make commander without those powerful tools more attractive. It is those commander that need to nerfed and not other commander that should be buffed.
Again, partisans are important part of the problem. Even if call them "cost efficient", it's no real reason to take this commander over other Soviet commanders with infiltration infantry units.
In this thread it has been claimed that partisan are UP. They are simply not UP. They are more than cost efficient. Are they enough to carry the commander? Certainty not but than again you can not expect Soviet infatry to be as attractive as IS-2, KV-2, ISU-152...
As for airborne guard I doubt many people pick the commander for ABGs and I doubt they can carry the commander. It mostly used for the SVT and rocket strafe.
It would work better, because you will have one partisan squad, which infiltrate from the building and have some upgrades, like Taksin02 suggested.
P.S. It would be cool, if partisans can interrogate wounded soldiers and get weapon slot, which they have when were alive.
My question was the mechanic and weapon upgrades is way but I doubt that many people would prefer the shreck to be an upgrade.
To summarize Partisans are not UP. If they do see action is not because they are UP but because there far more attractive commanders.