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Their tactics were really primitiv, but worked.
Mostly like WW1 battles + good support.
There are some good videos analyzing the eastern-front. And when you see how Germans won battle after battle, and even counterd some counter-attacks without having any chance on paper, you see the the soviet in an other light. Even Stalingrad wasn't that huge victory. But Germans weren't able to compensate.
Germans had one huge tactic disadvantage (beside no fuel, no winter-textil, no ammunition and or food) it was artillery support. They were unable to counter soviets artillery, and Soviets knew that.
Udssr mainly put their production priorities in Mortar and Artillery production. To destroying german lines (didn't worked well, but one dead PaK and crew can mean 5 T34 losses less, means infantry can attack trenches in cover, means MGs were useless means Germans had no chance). Also T34 were made for one battle, after that their engine was defect.
The real heroes of Eastern-front were German PaK crews and HMG supporters.
Edit: Kursk and other Soviet tank-victories were made, because Germans tried soviet tactics. PaKs and HMGs, Germans run into them + bad use of own material.