because Pac is LW fighting at WW and Floyd a JWW at WW who rely on their speed. They’ve already packed on plenty of weight since their peak days. Every other WW puts on 10-15lbs fight night. Hagler was a career MW. He trained and kept his weight down all year round. If he had the benefit of putting on 10-15lbs on fight night safely, he would have packed more muscle on. Floyd and Pac wouldn’t put more weight on for the sake of it, there’s a point of diminishing returns when you become too musclebound and stiff. Hagler packing on an extra 5-10lbs wouldn’t have affected him 1 bit, except carry that much more weight into his punches.