I agree with you on the importance and necessity of getting rid of dead weight.
All I'm saying is that stack ranking might not successfully get rid of dead weight. As with any system of metrics, the people who game the system are the ones who reap benefits from the system - thereby subverting the system, and preventing it from achieving its stated goals. As systems of its kind go, stack ranking is particularly insidious and gameable.
I have no idea what _would_ work, though. I have some half-baked thoughts, but will reserve them until such time as they are better than half-baked.