He doesn't appear womanly to me, perhaps his pronounced butt is due to the cocked hip stance he adopts. That does tend to shove one's ass way out there, and being an athletic-looking ballplayer, he probably is well built and thickly muscled around the ass and thighs.......good for running between bases! Football players (American football that is) tend to have larger and more pronounced bubblebutts due to the specific training and conditioning exercises they do to give them lunge power and running/tackling strength. Those skills need hard hips, thighs and butts.
Most of these athletes develop stamina and enhanced endurance with squats and leg raises, along with other exercise routines. Squats specifically will built a pretty large set of buns over time.