Adding- regardless I'd think the vast majority (90% +) of balks are called and enforced prior to the pitch, for any (and many more) of the aforementioned infractions. About the only way I could imagine a balk resulting in a live pitch is if the pitcher doesn't come fully set at the waist prior to making his movement toward the plate.. That call would have to be instantaneous to stop the pitch and if the 2nd base umpire rather than the home plate umpire, makes the call, it may allow for a pitch to be thrown.
I'm firing from the hip here (traveling/using phone only) but if anyone with good Google access could clarify further, I'd love to read more. Balks confused me enough when I was playing.
