Love this
Grit/heart overlaps with determination not success, imo.
I would agree with that. I size up competitors by three qualities: mental toughness, talent/ability and hunger for victory (aka killer instinct). I put grit/heart in with killer instinct.
I am thinking of this one guy. The head was his point of weakness. He had no mental toughness so he made a ton of mental errors. He had decent natural talent and some developed ability. His strongest area was the hunger and determination. That made him an intense competitor. But absent mental strength he would lose his cool quickly and start over-reacting to his opponent's maneuvers, taking it too personal. That would just totally derail his entire game and mental errors multiplied. Opponents were also supposedly getting inside his head. His intensity would boil over into wildly aggressive play. Still, though, he had tremendous heart and grit and could get "hot"...in the zone perform as good as anybody in the world for that short spurt of time. I always said that gave him a fighter's chance at winning...he usually didn't win but on the rare occasion he did it was a show.