And a single panther can kite an IS-2 from here to Verdun. Panther is faster and our ranges the IS-2. Troll it all day erry day.
You're really really not playing both units to their strengths in that example. Panthers excel by making use of their long range and superior mobility to stay at ranges where other tanks cannot reliably penetrate- or even fire back at all.
IS-2's excel by keeping other tanks close where it's not going to miss and can make use of a large HP pool and even thicker frontal armour to out-slug more mobile tanks that could otherwise simply rotate out for repairs and tie it up forever.
The Panther is actually a surprisingly terrible kiting unit against other heavy tanks. Far accuracy is pretty bad from maximum range. From my experience, the IS2 will more or less match the Panther's max range. From the front, kiting an IS2 is more or less useless.
The frontal Armour of the IS2 is almost twice the pen value of the Panther's main gun. From the front, you'll penetrate roughly once in every two shots. What that means is, you'll statistically be able to pen from the front every 18 seconds (Assuming the round actually hits). Whereas you need something like 6 shots from a Panther to kill an IS2(18 * 6 = 108 or just under 2 minutes, completely ignoring the (actually quite large) chance of a miss), the IS2 only needs 3 shots on the Panther from the front, whereas it has a 75%-ish chance of penetrating.
All in all, Panthers are terrible against IS2s. Hell, King-Tigers are actually fairly bad vs IS2s, let alone Panthers. And yeah, they're massively overpriced for what they do. Essentially just a glorified T34/85 without any of the AI-capabilities.