"It's old data. The "Hogs" mini-Hogger pet is not a reward from that achievement, and we'll correct it in the next PTR build. We haven't determined yet if/when he'll be obtainable, or from what source."-------------------------------
A new patch was released onto the 6.1 PTR today, and a new pet was added. Grave Golem, previously named My Special Pet, is going to be a reward for an achievement related to Heroes of the Storm. No details on what we'll have to do to earn Hero of the Storm, but as a non-moba player I hope it doesn't require something too complicated.
If it's something similar to the Hearthsteed achievement, Hearthstoned/Mount Up!, I think I could live with that. I'll just need someone (probably the OH) to carry me through a few Heroes matches haha. I apologize ahead of time to any serious Heroes players that have to suffer through a game with me. :P
Another change from the PTR was reported by MMO-Champion. The source specifically is notable because MMO-Champion seems to be the only one reporting this -- Hogs now a reward from the anniversary achievement Victory In Hillsbrad. Wowhead doesn't list this change and Hogs is not in the Pet Journal on the PTR.
IF this is not a mistake in datamining and Hogs WILL be a reward for an achievement that's no longer obtainable, I foresee a large portion of the community being ticked off. Yes, it was briefly listed as the reward for the PVP Feat of Strength early on, but that was removed before the anniversary event rolled around. There was no notice that this would be reverted yet again, and Hogs would eventually be retroactively rewarded.
So it's only natural that those that skipped out on the anniversary BG would be upset if the pet is ultimately the reward. Had there been some sort of early warning, I think more would have participated in the BG just to earn the achievement for this future change.
But, as I mentioned before, only MMO-Champion is reporting this. It could be a simple datamining error. Or Hogs might be a reward for something else and the anniversary BG achievement is just a placeholder until the actual achievement is implemented. All we can do is speculate for the time being and wait and see where (if anywhere) Hogs winds up. I wouldn't panic yet; the PTR is known for changing.
I have to admit that news of these two pets does put me a little on edge, though. I'm not one for mobas or PVP, so even speculating that pets might come from these two sources makes me anxious. Ahhh :(