Drill sargents are paid to bully IMO. They tend to pick on congenital screw ups and others that stand out in the crowd. There was one fella in my platoon that was a polite sort, big by most standards. The DI's were merciless.
We were doing bayonet drills with the M14 and they started busting his chops about how a big guy like him couldn't stick the bayonet in the practice dummy any more than a few inches. It was a steel frame that compressed and contained strips of car tires about 6" wide, the frame being roughly 2x3' in size. It was sad watching the whole thing actually. No mercy at all.
Tiny finally snapped and drove his rifle through the tire rubber all the way up to the trigger guard. They had to disassemble the frame to free the rifle
They never gave him any crap after that.
It wasn't until graduation day that they found out that Pvt Tiny's (Enlisted Reserve) day job was that of a defensive tackle for the Detroit Lions.
