47 isn't really high. There are 30 starting jobs out there. So if you're like a mid-level backup framer, can't play defense, can't hit, can't do anything else really, you start to see where his shittiness comes from.
This is also useful with DRS. DRS/chance and even UZR/chance (UZR/150 doesn't capture certain guys getting more chances/game) paint a better picture as a whole. Then you can put it into a + format with league average as 100 so that you're not staring at a bunch of decimals.