In most cases teams that are trying to get under the cap will be measuring it down to the decimals. If so, the value of the rookie you pick does matter. There 14 rookies with a PB value over 2 and 34 with a PB value greater than 1. It may come down to being forced to take a prospect with little MLB time last year instead of the guy you really want. If you know the number you can decide whether you can take Ryan Doumit (PB Value-1.735)or instead have to take a flyer on Jeff Mathis (.010) because you can't squeeze in the extra 1.725 towards the cap.

Quite frankly, it's no wonder your teams are nowhere near the cap if you can't figure this out.