Oh it's probably a handful of things. That fire that burned through there in 2012 must have changed the brush communities in there (used to be huge flats of bitterbrush), which I'm sure doesn't help forage quality overall. I think that there has been some hunting pressure from essentially OTC bow hunters too. Not that their efficacy is that high, but I think folks that travel all the way out there are likely to kill a deer if given chance. All speculation of course, but that would be my sense.
When I hunted the NV side, far and away the biggest buck wasn't anything particularly spectacular (IMHO), but was generally regarded as a good one by the folks we spoke with out there. He had a big frame, but even in a really wet year (2019) it just seemed like he didn't "finish" at the ends of his tines. Not to take anything away from the deer or the hunt (which was spectacular), but if you're looking for a true giant I don't think it would be my first choice.