It's not even the Sp.D that kills Rhyperior: It's the "Hit me and watch me die" typing of Rock/Ground, which is literally one of the worst typings to have, combined with Rock/Steel.
Rhyperior will always be UU for all eternity. It's strong enough to eat a couple of special moves - even low BP quad effective ones at that - but it has a variety of issues. Yes, the Rock/Ground typing is probably the biggest issue, but it would be very happy to have a slightly better Speed (+2 Rhyperior needs jolly to outrun base 115s and, in teh case of UU (next gen's, anyway), it actually needs to run speed to sub before chansey toxics... this is true of all slow base 50 mons), less shitty STAB (yes, edgequake is unresisted as a whole, but stone edge is not reliable and, awkwardly, resisted by a lot of what earthquake is necessary for, lessening the viability of choice band; earthquake is simply not a spammable move outside of gravity), and better coverage (a lot of the things that edgequake hits neutrally are things rhyperior more or less cannot really go up against... granted, you can do things like poison Tangrowth / Slowbro / something on the switch, but there should not be as much prediction in move spamming with a mon with 140 base attack and 100 BP STABs).
@Azumarill being good
The main issue that azumarill faces is less its STAB / lack of resistance to Dragon and more its inability to handle much of OU effectively. Water types essentially give azumarill the middle finger unless it's running subpunch (which is a kind of mediocre set in its own right due to its horrible 4mss, among other reasons) and grass types do the same since ice punch is so hilariously weak. They can't take repeated abuse, obviously, but neither can azumarill, which lacks any sort of recovery. Being more or less forced to run Choice Band introduces issues of its own since being locked into pretty much every one of azumarill's moves is never all that great.
If Azumarill gets a 100 BP Fairy Quake or whatever it's going to be, sure, it might go ok, actually, largely depending on what exactly fairy will allow it to hit neutrally. Until that happens, though, I don't see it being too relevant unless excadrill is unbanned.
