I took a whitetail this year that weighed well over 200 after I gutted him, then the guy I was hunting with shot one that was so small I hauled him to the boat over my shoulders. Go figure. 4 years ago I shot a mulie about 1/2 mile from this year's whitetail. It was a freaking pig, about the size of the pictures you posted. Quartering and hauling him out was nasty work.
The common denominator is that the area where I hunt has a massive alphalfa field next to it irrigated by some wheel lines. Wish I could hunt right on it! The deer munch on the alphalfa all year and fatten up very nicely. Those with the proper genetics have plenty of food to reach their full potential.