A lot of people comparing Rory to Hendricks; Hendricks has a lot of mass but he is 3" shorter and gives up around 7" of reach to Rory. Rory actually has a reach comparable to Anderson Silva; at MW he'd be just as big as anyone else. Of course that doesn't mean he SHOULD go to MW, but people shouldn't be saying Hendricks is the same size as him because he's actually much smaller.
While a guys weight is important, the size of a guys frame is even more important. Guys like Hendricks and Alves pack on tons of muscle to try to make up for their small frames; they cut a lot of weight but it doesn't really make them bigger then the other guys. In some situations being compact and muscular is an advantage, but the overwhelming majority of top fighters have long, lean frames.
Zombie is born!