Mike,
You can't just look at the cuts made by high Cap teams to determine the effectiveness of the cap. You have to look at all the trades being made by high cap teams leading up to the drafts and cutdown day. I have seen many trades go through in which it seems apparent part of the motivation was a need for one team to shed PB points. While it may not be as dramatic as having some top players cut on cutdown day (which I doubt will happen), it certainly has had the intended effect of spreading talent around the league. Mike