Sure, It has been known for some time that athletes start losing motor nerve responses VERY EARLY. So, you see really young gymnasts (Chinese sneaking underaged girls into the Olympics), table tennis (almost all reaction time) players peak really early. Running backs in the NFL rarely run for more yards per carry than they do in their first couple of years. It goes on and on.
Anyway, regarding KVD, surely he has lost some of these physical aspects; but, he has a personality characteristic that is very hard to come by: he is unflappable. One guy on his boat said in one comp, KVD hooked and then lost a really big bass, might have even done it a second time and never blinked, showed no frustration and that KVD told him that he remained positive because he knew he was on fish and using the right tackle . . . something like that.
He'd be sort of on the opposite end of the "frustration" scale from, say, Iaconelli in this regard. But, it means KVD makes more casts not throwing temper tantrums, stays positive, that sort of thing. It nets out more casts and more casts means more victories.