Nothing, Canelo was just able to take it. His head movement is underrated. Even when he took a shot a lot of the time his head was turning away from it, reducing the impact.
Do you know how you can tell Canelo was scared of Golovkin's power? Watch the fight, he was in full retreat. No need to do that if you aren't feeling your opponents punches. Even when Canelo has success in the center of the ring, he was too fearful of GGG's power to stay there. On the other hand, Golovkin walked right through Alvarez's shots.
It was there , you could see Canelo avoiding it .In the other hand GGG was getting hit and coming forward like nothing happened.
He pressured, backed Canelo up, and landed more punches through most of the fight. But he did not land many clean shots. His accuracy was way down this fight and a lot of that was Canelo's defense and quickness. GGG clearly won, but never landed his best shots. Hence the power was less a factor.
I would put it this way: 1. GGG landed his best shots. 2. Canelo's chin's now legit. 3. GGG just managed to land singles and too far in between.
He couldn't land anything substantial in rapid enough succession. Usually his opponents get REALLY ****ed up when he's just pounding on them over and over and over and over with power shots and then eventually they're just done. This fight he landed a few hard shots and Canelo either managed to avoid followups and protected himself until he recovered, or GGG backed off. I think one shot had Canelo hurt, I forget when. He wasn't chasing with as much enthusiasm as usual, more caution. Also I think his power is diminishing (it SHOULD be with age) and will diminish further. I thought this would be the fight he would lose, but I guess it will be one of the next ones. If they stall the rematch and have it in another year I think GGG will truly be done. He just can't last much longer if he's human, apparently his skull is abnormal so maybe his chin will never crack, but his power is his biggest tool (his ability to get his opponents into vulnerable positions is what lets him use it best) and it's just going to degrade more and more with age.
Golovkin does not have a normal human skull/brain. There is something seriously alien about it. I don't think him taking shots says anything about the opponent's level of power.
Fighters score less knock outs as they age, and you won't find a fighter that bucks the trend. Even Maricano and Foreman's ability to put fighters away decreased as they climbed up in years.
Everything? Nah....Nelo landed at 33% and GGG landed at 31%. Golovkin actually landed 49 more shots than Nelo. The way Alvarez was back peddling forces GGG to chase him around the ring so it affected his connect percentage a bit. Nelo had proficient D, but was getting caught quite a bit by Golovkin with the jab, right hand and left hook.