Babe Ruth
Mo Vaughn
both Fielders
CC Sabathia
David Wells
Bartolo Colon
Pablo Sandoval
there's probably more I can't think of at the moment.
Does being heavy/fat potentially reduce your career longevity, yeah probably. But especially early in your career it doesn't necessarily have to have any impact on your performance level. Vladdy's going to have to keep his weight under control to make sure he doesn't break down into his early 30s, but he's also not at the size that some of those guys were so it wouldn't likely be as pronounced a decline. But for right now it definitely seems like there's other things in play causing his struggles besides "lololol, he's fat"
It's the same lazy analysis with Kirk and Manoah too. "eat a salad, bud" is some lazy analysis.