The point he's trying to make, is that even though Lebron isn't as good as Miller/Allen from 3PT range, his JS doesn't get worse from that distance. He's not as good because his JS isn't as high as Miller/Allen, but it could still be that his BB skill JR is 20. A 15-20 (JS-JR) player in BB will shoot a lower 3P% than a 20-20 player, so Lebron could be a 15-20 guy while Miller/Allen are 20-20 guys.