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Jack Wilson being the reductio ad absurdum.
Sticking his head into crosses, taking elbows in the chops, stuff like that, may have just drained him of all fear as far as a little 3-inch baseball bouncing along the ground at him.
From an aiki standpoint, Wilson subconsciously wants the ball, welcomes it as a friend ... other guys fight the ball as an enemy, and it shows in the stiff hands.
Never thought to intersect that with, say, soccer or basketball cross-training.