Timing. Canelo will be barrelling into this fight with a full head of steam (string of wins), much to prove (being called a duck), and a confidence that is retard strong (feels he can compete at 160+ after taking apart such a big guy in Chavez Jr.). Golovkin, in the eyes of some, might be slipping. Mid-thirties is when fighters naturally start to slow down, it's been in the history books for forever. I love the exceptions when the older fighter wins (like Foreman against Moorer, or Hopkins against Tarver), but Alvarez is just getting better at what he has always been good at, whereas Golovkin is being accused of slowing down and being "exposed".
All of my analysis tells me that GGG should win this fight. He wasn't exposed, people that have eyes know of his weaknesses going into the Jacobs fight, and honestly, with Brook...a welterweight that good is gonna steal two rounds from ANY 154 or 160 fighter. They are faster and usually have quicker feet. It's down the stretch where weight tells and this was the case in Brook's defeat. Imagine Brook as a naturally size MW? He'd be near or at the top of the heap. Anyway, I don't see Golovkin looking old or slowing down. I also don't see Alvarez as a fighter that has improved his weaknesses - we just forget them because he keeps dominating. His feet suck, his conditioning won't get any better as he puts on more muscle. And GGG? He is gonna put the mental and physical pressure on Alvarez.
The power, chins, body punching of both men, and Alvarez's ability to stay focused and sharp for a full twelve rounds without getting lazy, like, at all, will be important considerations.
The old rule that a good big guy beats a good guy moving up in weight might hold true here.
The sparring notes from 2011 were interesting. Alvarez never shook GGG, but GGG hit Alvarez so hard that Alvarez was walking around, shaking out his foot between rounds. How much has GGG declined since then? I wonder.