Hindsight is 20-20 and I'm sure the NFL sees letting these issues to be negotiable at all a mistake. They should've known that agents are looking to justify their existence, so will pick whatever fight they can. On thee other hand, it might be an artificial line but the Chargers know damn well that they're well above it, and are being obstinate. To answer your question Patler, since the new CBA has been in place, no #3 pick has had both deferred money and offset language.
I agree with pbmax that teams want to hold onto the money because if the player goes off his nut, they have a much better chance of keeping it than trying to get it back. Manziel managed to not get paid for the last two years of his "fully guaranteed" contract.