There are several other variables to consider here for why people consider this a dominating fight in Martinez's favor. Skip b and company conveniently keep leaving out the fact that Chavez JR has a habit of outweighing his opponents by 20 pounds. nikka looked like he just came from Auschwitz at the weigh in and balloons up to LHW and Cruiserweight levels over night (Personally, I think this is a scummy tactic but gotta hate the game on this one). Chavez uses this advantage and it works with his style. The weight advantage lets him take shots that would hurt smaller guys while he can impose his size over the opponent and walk them into the corner and start pounding on them.
Reason why people were impressed with how Martinez handled dude is because he obviously came with a plan of boxing on the outside and using his foot work to blunt Chavez's plodding but imposing style. Like Roy Jones said, due to his movement, and given the way Chavez's fights, he has to reset and try to setup his attack but the footwork throws a wrench in that shyt. Also, given Chavez's size and just the nature of the game, Sergio was bound to get hit and given Chavez's size advantage, that shyt is going to hurt but Sergio still stood there and traded with him at times anyways

. On paper, all the physical advantages are in Chavez's favor but he just got outworked and outsmarted.
Also you folks keep saying, "oh he wasn't trying" like he had some latent skill he didn't unlock during this fight like a super saiyan or some shyt. JCCjr tried to use the same tactic he used in the andy lee fight which is the basic "walk them to the corner and pound away". There is no skill there just brawn brehs.