The Panther is balanced but it isn't exactly your first choice.
For OKW the Panzer IV is almost a no brainer offering way higher damage output in total.
The Ostheer meta seems to evolve into Brummbär rushes. Then the Panther becomes a choice lategame. Not because it is such a great unit but because it is available in the same tier as the Brummbär.
I think the best way to adjust the Panther is to fiddle with its veterancy. The concept of a diving tank hunter with Blitz is strange to balance. Using it "correctly" (aka diving in) means using it "wrong" at the same time (aka exposing your weak rear armor).
Give it another vet 1 ability instead of Blitz that increases the damage output for some time (rate of fire or maingun damage) so it can hit hard. It wouldn't have to dive as far and expose the weakspot since it could deliver the damage faster. This way you would keep the nature of the Panther as a shorter range heavy hitter without mirror balancing it towards other tds.
