Alistar in the Jungle
To begin, I'd like to state that I wasn't around for when jungle cow was popular. I started in the middle of season 4, and I've picked up Alistar over the last few months. I've played him in most roles and different compositions. However, I really like playing him jungle.
Now, Riot has stated in patch 4.20 that in the presseason jungle they were aiming not to have to nerf the optimal junglers, but create a new jungle where strategic diversity could thrive. To do this they made the new jungle much harsher and stronger (20% increased base health and AD, as well as greater scaling in small camps). Champions with sustain are rewarded in the new jungle, and damage heavy junglers (i.e. the original optimal junglers) have to balance themselves carefully to be able to gank lanes safely whilst being able to return to the jungle as well. Tank junglers, though, have an odd place in the new jungle. In the old jungle, they were able to use the Quill Coat passive as a sort of crutch to make up for their low clear time and have adequate clear. In the new jungle, tank junglers can start Gromp for a measly twelve magic damage over three seconds at level one. Theoretically, one could have the buff always on to improve clear time, but it is impractical. Now, not all tank junglers are unhealthy in the new jungle. Some do very well from what I have seen, though I do not have personal experience with many. So, to revisist, junglers with sustain can simply stay at a relative safe level of health, damage heavy junglers can clear quickly and rely on itemized sustain, but what can tank junglers do? Most cannot absorb the damage or clear quickly enough to avoid losing a substantial amount of health (barring sustain tank junglers).
Alistar is unhealthy in the jungle. He cannot clear quickly enough to avoid the damage he is forced to take. He cannot sustain well enough nor absorb all the damage. The changes I propose would be either to revert his passive to its state before patch 4.12 or rework his healing ability. I believe the former will do the trick, because originally that was nerfed to stop him from thriving in the jungle. The jungle is stronger now. It will balance itself out.
Thoughts
EDIT: After some testing and more research, I've found more ways to improve his clear time and sustain. He is slightly more bearable, but I do think he should get a buff to improve how far behind he gets vs. other champions in the same situation.
ult, which is somehow cheating.