^^the only different in pac's physique really is that he isn't wieght draining himself to make the smaller weight classes anymore.
Pacquiao has walked around at 150+ for 5-8 years now at least.
When he fought at 130-135, he had to cut a lot of weight before weigh in. Then he'd rehydrate to over 140 pounds on fight night.
The difference is now he doesn't have to cut that weight. He looks so much more healthy during weigh ins.
Pacquiao at 130 pounds 24 hours before the fight:
Pacquiao at 144 pounds 24 hours before teh fight against cotto:
His face is fuller now and not caved in and not weight drained like he was before, that's because he's not dehydrading himself to make weight. He actually eats breakfast & lunch the day of the weigh in whereas before he couldn't eat anything for 24 hours and very light the entire week before weigh in.
Additionally, he grew into into his body. That's common for fighters to get bigger as they get older, especially if they turned pro as a teenager. Look at Floyd Mayweather. The man is ripped at 147 now. It's the same story for Floyd, he grew as he got older. The difference between the two is Floyd is an extremely defensive fighter, he doesn't try to KO anyone.
I'm just not seeing pac juicing. He wins by his skills and training hard. His punches that knocked down cotto for example weren't crazy power shots, they were perfectly timed shots that came at angles cotto didn't see coming. That's skills.