@antrad You are right! I think that that texture does not look like rocks only: rather than a pure surface, I visualized roots, dirt, dead moss, etc. (like the image below).
Something similar like in the game Hunt: Showdown, where there are huge piles of dead organic material, such as the base of a tree long fallen, with all its roots exposed still clenching dry soil and little rocks (can't look for an example right now).
That would be a design choice only if we were to define how a satisfactory output should look like, but your example provides what should become marks on the rocks, and your video shows clear improvements which are almost magical (like putting on my glasses!).
I think that a good way to see how to improve this specific texture would be to take a look at its adjacent ones during gameplay, but to give you a better response, I should learn more about this technology.
The one with the yellow flowers is truly impressive!
Also, making that surface look like more than just rocks could change the game's visual languaje, which is intended to be bit cartoony, so that kind of upgrade could go against how the whole composition should look, which reminds me of games' concept art: the results in the video are so good that it looks as if the game became more "itself", as if it where turned into an even more "original" version, closer to concept art, rather than merely being upgraded.
So it would be interesting to see the result you are looking for and compare the scene where it is being applied, just like you did in the video.
I currently don't have time, but it would also be interesting if I modify with Photoshop this texture to make it look like what I think you want.
I'll see your blog's content in more detail after the exams; it looks very interesting! And I loved this title:
Fixing a GPU by baking it in an oven - It actually works !