Depends on what the faction is suppose to face.
For calculs: (60/(Reload time))*(damage per shot) with some approximation you have the true DPM (without pen/bounce/deflect damage/miss ect... which could turn the calcul into nightmare).
An heavy tank is meant to be reliable in every way and be really good at tanking damage in exchange for mobility. It is a balance really hard to achieve because, if it is not good enough, other more "specialized" unit are better. And since the only target a Tiger is better than the other against is other heavy tank, which also got nerfed and vanished, the Tiger is not a worthy AT option, so it remain AI. If its AI capabilities are good enough, it could be a viable "bigger" P4 in its role, but turns out it isn't, so building one is risky due to the high amount of ressource to spare and other inconvenience which goes along which the "BIG ONE" archetype which were told before.
The ISU isn't properly OP, even if its AI performance seems unfair. It is exactly what power an heavy tank should have to remain an option which overpass the medium spam. With the nerf, those 3 heavies (IS-2/Tiger+variant/Pershing) kinda lost their identities (the IS-2 case is a bit special).
So yes, those nerf were intended for 1vs1 and their effects weren't sure by the time of the patch release. We waited several mounth and tournaments to be able to see exactly what happenend. The results are that the Tiger is no more used in any game mode, whether it be the 1vs1 or 2vs2 tournament, or from my own 3vs3/4vs4 experience.
We can no longer say that those nerf were beneficial and anybody against is just a idiot Wehrboos relying to much on its "OP toy" to win. Whether it be the overall impression or the stats during big events, everything point out that those nerf were disproportionate. Maybe it solves the Heavy meta in 1vs1, but it destroyed the diversity every other gamemode, limiting the Ostheer with the Elephant or the Infantry doctrine. And I find it legitimate asking for a buff which could allow us to have acces to a greater variety of commander,whether it be for the Ostheer, the USF or the SU. ( 5 Ostheer commanders have the Tiger or a Variant)
Due to time constraints, I will make a more elaborate answer later and this one has to be shortened.
Apart from that formula not being correct, what you term "true DPM" does not account for one of the most important factor: penetration. According to your formula, a Puma (1870 DPM) would outperform even an SU85 (1770) and apparently also almost the Tiger and ISU by far (see your numbers). At max vet, it would have a whopping 3116 DPM and even beat a vet 3 Jackson (3018). Now this gets even worse if you would take the correct reload formula because the Jackson has wind up times which forther prolongs the reload. This number says absolutely nothing and you cannot make any serious point with that. And these "nightmarish" calculations for penetration are quite straight forward maths. The only "nightmarish" aspect is calculating scatter hits but you can easily take the next step towards penetration. If you are not willing to do this ask for someone to provide the values, but don't try to make a point with raw DPM that actually says more about the rate of fire than about actual performance.
Now to the point:
Tigers (like Pershing and IS2) are meant to be generalist heavies. We previously saw them in literally almost every game. There are two options for that: Either the faction is unplayable without it, or the unit is vastly overperforming.
This role however included that they should be jack of all trades, but worse than specialized units at their special task. Pre patch heavies wiped models and sometimes even squads like specialized AI vehicles (Brummbär, Bulldozer Sherman), being able to attack AT guns while still having enough AT performance to fight off any armor that was thrown at them.
Their AI has been toned down quite a bit. The extend of it is up for debate obviously, but these units were vastly overperforming. SOV and USF have seen only slight adjustments and the factions are absolutely fine even without a heavy, arguing that the previous AI profile of heavies was too strong. For OST, this point is not as easy to make since the whole faction has seen some buffs, but looking at the stats the Tiger's AI performance is not that bad (have to search for MMX's posts somewhere, he has good data) compared to other heavies while still being good at AT.