6 years later than it should have, the mega fight is finally gonna take place.
Basically, here's how I see it:
Both men have declined, but I feel the decline has affected Pacquiao more due to the natural regression one suffers to their athleticism as they age.
Floyd relies on defense and counter punching, most often 1 or 2 punches then moving away. That style is not affected with age as is speed, power, and workrate which are all of Pacquiao's greatest tools.
I had zero doubt that Pacquiao would've defeated Mayweather 5 years ago. But while I'm not so certain now, I still believe he can and will win for the same reasons I believed in back then. Floyd has never fought anyone who could match him (or at least come close to macthing him) in hand speed. But not only does Pacquiao have the speed, he has the best combination of speed and power out of anyone the sport has seen in the last 15 years.
Floyd has avoided fast, technical guys like De la Hoya, Zab Judah, and Shane Moseley. He's made a relatively easy go of it against strong, stationary fighters like Canelo Alvarez and Maidana.
But none of those guys possessed all of the following traits: Speed, power, technical prowess and top notch precision - except for one, and that was Miguel Cotto. That's why it is no coincidence that the toughest fight of Mayweather's career, and the only one that truly saw him take some physical punishment, was against Miguel Cotto. Cotto used those traits along with an excellent plan to attack the body to make Mayweather suffer like no one has ever seen. It just got to a point where he just couldn't land enough punches to win a decision.
So now you take Pacquiao who can do all of that but to an even greater degree. He's faster, quicker, more precise, and throws more devastating combinations. If Cotto could get to Mayweather, then so will Pacquiao.
It is my belief that while Mayweather will frustrate Pac at times, it will be impossible to avoid punches for the entirety of the fight. And once Pacquiao begins to land enough punches to start winning on the cards, Mayweather will have to go on the offensive which is not his strength, nor is it something he is comfortable doing. That is when Pac will land even more punches, and do what no one else has done before and beat Floyd.
Pacquaio wins on points.