In addition maybe TT looks at it like a one-year, $8.5 million deal as it actually doesn't make any difference if he would count that much against the cap this year or $3.5M this year and $5M in dead money next year.
Either way, I would be furious if they let Nelson or Cobb walk away because they didn't want to have dead money counting against their cap and because of it gave up $7 million of cap space.
I'm reminded of Hawk's dreadful 2011 season after which he should have been cut or renegotiated. The dead cap was too large to give Thompson any leverage in renegotiation so he was stuck with the player and the contract. Burnett is in a similar situation today...not only do we have to pay him, we have to play him with optimism that he'll snap back.
Taking a $7 mil cap hit in 2015 with the expectation that we'll have the 2013 version of Peppers for one more season is within the bounds of reason. You also need to consider the cost of replacement. That's why the deal is structured the way it is to the players benefit.
If Thompson drafts Hageman or a somewhat lesser light in the second round who fits the 5 tech / 3 tech "length" profile, I will admit to having misread the situation. But it seems to me that with the signing of Peppers that ship has sailed for this draft.
Besides, you should look at some of Hageman's tape on youtube or nfldraftscount.com. As I noted earlier, the guy plays high in his stance and has a habit of standing up at the snap. That might be fixable. Or maybe he needs to do that for visibility given some peculiarity in his build. There's a big risk here that he's more athlete than football player. Or perhaps he's really a standup player by nature pumped up to play the line; we already made that mistake once with Neal.