I agree with OP actually, just posted it on the Red Army Strats page asking about it. And he is not exaggerating.
Recently I have been playing games where we dominated the map for over half the game, getting the germans below 100 VPs before they come back with a KT and 2-4 panthers, completely pushing back MULTIPLE IS-2s backed up by AT guns and SU-85s (this is in 2v2s).
The Panther can tank a ridiculous amount, is super fast and has a great main gun with superb penetration. It can even hold off infantry to a certain extent.
I also agree with OP. I have played several games in 3s or 4s and allies had 3/4th dominance. Than out of left field comes mass tiger/panther/kt or whatever completely pushing and destroying.
I just watched a replay today in fact where the axis played passively and quite poorly actually. When it came down to 50 point they blitzed a massive tank squad in to take out multiple is2s/at guns/ etc... wining the game.