When I read your post, I thought of something: my SF's driving is atrocious (I know, I know, but I'm playing in IV. league...

) while Jump shot and Jump range are both on respectable. His shot was blocked twice in a game when he went for a layup/driving, but his midrange 2-point or even 3-point shot was never blocked in any game (at least I didn't see that).
So a player can have SB Inept and will still block my SF's layup from time to time; but if said SF had driving Respectable, the player with Inept SB wouldn't block him in a million years. So that's probably that calculation you were talking about?