Well, give us an example batting line up? If it's weak batting, the batsman. If you have a good packed batting line up, hopefully with good balance, then you could have that option of taking the keeper. If the batting ends at 5 or 6, and you have a true keeper coming in maybe after the bowlers, or lower down the order, you don't have many tail ender runs, and would get bundled out for lower scores more often if the top order doesn't fire, as happens regularly in current cricket.