I don't like shots for as an offensive stat since it can arbitrarily rewards guys who skate down the wing and loft wrist shots into the goalie's chest (the Sabres have a few guys like that). For defensive GVT, I can live with shots against being included since it isn't a big component and should loosely account for things like blocked shots. And, shots for is by one person (that player) whereas shots against is by all opponents (multiple players). The whole GVT stat is pretty convoluted. But, I like the attempt to value every player in the league, regardless of position. And, it appears to have a little bit of face validity.