Although I'm not loyal to Mayweather, I respect him as a fighter and his incredible undefeated winning streak (almost as impressing as Julio Cesar Chavez's winning streak in the 80's and 90's), to answer you question yes Canelo's size and strength can be a major and determinate factor against Floyd, but that will not be the defining factor for beating Floyd, unless he can land a wild punch that will hurt Mayweather and put him to sleep or on the canvas. The key factor for Canelo will be his STAMINA. If Canelo gets tired he loses, if he doesn't get tired then he has a good shot of winning by putting on constant pressure on Mayweather. I will be rooting for Canelo, but I would never bet on this fight because it's just to hard to tell who will come out victorious. Sure the favorite is Mayweather's and most of the bets are in his favor; the saying goes "If you want to win money then never bet against Money". The biggest factor is whether Mayweather will be the same during this fight, or will Canelo's youth and strength will prevail, and achieve the one thing no other boxer has done before and beat the undisputed King of boxing. Yes Canelo is a big boy and he has punching power, I don't think Mayweather has the power to knock out, knock down or even hurt Canelo and Canelo's team knows this, however all of Canelo's attributes will not mean a thing if he can't land a clean punch at Mayweather. Another determining factor will be Canelo's stamina. On Canelo's last fight ( against Trout) he was more defensive in the late rounds and opted for fighting Trout without pressure, you CAN'T do that against Mayweather. If Canelo tries to outbox Mayweather, he will lose, If Canelo gets tired in the later rounds he will lose, doesn't matter his size or strength. The only thing Canelo can do is put on the pressure against Floyd and try to land hard punches to the face, body, and even arms, just like Oscar de la Hoya, and Victor Ortiz were doing before the former got tired and the latter made the stupid mistake of headbutting and asking Floyd's forgiveness before getting Knocked out by Money. If Canelo can pressure Floyd through out the whole fight WITHOUT getting tired in the later rounds than I believe he has a great change of making history and beating Mayweather via Knockout or TKO. But if Canelo gets tired than it will be an easy 12 round decision for Mayweather. In short Stamina will be the determining factor for Canelo, and then comes his punching strength and size.
Yes, Floyd remains essentiallyl welterweight despite having fought twice before at jr middleweight. But your postulates about his past opponents as smaller are not accurate as all of them fought in higher weight classes at the start of their careers than Floyd who begun his pro career at 130 lbs. Hatton had fought twice before at welterweights vs. Luis Collazo and Abregu winning a world title in the process before scaling back down to jr welters to defend his title vs. Luis Castillo whom he kayoed with a single body punch. Ortiz was virtually a welterweight, even a super welterweight at fight time when he was still fighting as jr. welter. Cotto started at jr welter and he was a 147 pounder and a 154 pounder longer than Floyd. Mosley started out at lightweight but outgrew the division and moved directly at 147 lbs. and 154 lbs. Oscar started out at 130 lbs. but he was already many times welterweight and super welterweight titlist before Floyd moved up to 147 lbs.
About Canelo, he has a size advantage over most, if not all of his past opponents but that was not much of an advantage based on some of his results against them. Canelo has fought a Hatton but he was not Ricky but Matthew, a Cotto but he was not Miguel but Jose Miguel who were both blown up lightweights and he failed to beat them convincingly using his size and strength advantage.
But his size, strength and the improvement he has shown over his last few fights shouls really a source of worry for the Floyd camp. But I believe Floyd's better skill set and experience will help him overcome and prevail.
Deep down the Floydiot fans tremble when they hear Canelo
Look at Floyds past opponents who where good power punchers
Ricky Hatton-a natural JUNIOR Welterweight
Victor Ortiz- Fought below welterweight for most of his career and only his last 3 fights where at welterweight
Miguel Cotto-A shell of his oldself after 2 KO loses and a natural welterweight
Shane Mosley-a big guy but he was 39 when he fought Mayweather and struggled in fights above welterweight
Oscar De la Hoya-lets face it Oscar was 3 or 4 years past his prime and as a guy who relied on speed was so slow in his fight vs Mayweather but being 35 will do that
Canelo Alvarez
numbers show he trails ony Mayweather in accuracy so he's accurate and even though mayweather fans say he's slow Mosley and trout say other wise.(you would think pros would know more)
Also lets face it he's strong and hits hard he floored trout and before that fight I would have bet that no one could knock down Trout.
LASTLY He could fight naturally at Super middleweight and this is scary
Mayweather has never been in the ring against someone as big or as strong
