Yeah, I think it’s a different picture at different ages. Not like I’m an expert, but anything with good bloodlines and conformation is a prospect before it’s backed, and then the field narrows as time and training goes on.
Both of mine have the scope and quality of jump for GP, along with the breeding- honestly, I’m not being barn blind! But my older guy probably doesn’t have the extra je ne sais quoi that you need for the really big tracks- not heart, exactly, because he is a Very Good Boy and a trier for me, but maybe that bone-deep will to fight? He’s very happy to be directed and while he will hunt down the jumps in the show ring he’s not a self-starter. He will do what I tell him to do, and isn’t interested in making his own decisions. Also, he’s had me on his back bringing him along since he was 5, not some super-talented person, and at this point, in his early teens, he’s pretty happy and habituated into being an ammy horse.
My younger new guy is incredibly scopy with one of the best hind ends I’ve ever felt, but he is also so ridiculously extra-careful (like that second video posted above), and spooky, and sensitive that I think he’s better suited for an AO jumper life. Which is fine, because that is what he’s going to have!
So, there are some intangibles, too- you might have the athleticism but not the brain or temperament for it, or vice versa. And then the training is the other huge factor- if my older guy had been in a professional program instead of coming to little ol’ ammy me, perhaps he could have been made up into a big sticks kind of horse. My new one probably could, too, with careful management. But, they are ammy horses, so we will never know! I suspect there are plenty of really good jumping horses that have the potential but lack one or more of the key pieces to realize it.