This isn't anything new. It's just more frequent and common now. It used to be all the Michigan recruits. Now it seems us and Miami are taking a lot of the hits. I bet pretty soon if you go to the NTDP and keep your college scholarship, you'll be an outsider. The latest de-commit though, the McCarron kid, is a different case since he's just decided to go to a different school.
On a side note, I thought it was a pretty telling/interesting that Luke Voltin favorited my tweet that said him getting kicked off the NTDP was the best thing that ever happened to him. I guess he agrees! haha. I get the impression he was glad to get out of there. You won't be able to convince me that something strange isn't going on in Ann Arbor though. But then again, the NTDP doesn't care about kids keeping their college commitments. They care about getting kids drafted high.