The result of this is to put a premium on violating this agreement or on pushing its boundaries to the outer limit. The so-called "built-in" limitation on faking is exactly the same as the "built-in" limitation on slugging—"Don't slug too much, or we'll step up our own slugging." There is the difference, however, that the umpire who wants to avoid serious injuries can stop slugging, but can't stop apparent faking, precisely because to do so would be to run the risk of causing serious injury.
It is one thing to take a slight advantage of an umpire's slowness of visual response. It is another thing to take advantage of his desire to see that no one gets killed.