As always, I'm glad to echo faith in the Pats' FO, and Mo, good point about the climate being very different regarding trades. Miguel, while being a great capologist and much more learned than me, is also admirably circumspect about irresponsible speculation. Not so me!
Irresponsible speculation: If they were honest, BB and SP would mention the notion of risk management prominently, in explaining their positions.
Making cap room in a later year, out of today's "leftover" money, is one goal. Managing risk is another. We can categorize risk til the cows come home -- declining performance; injury, routine; injury, career-ending; etc., etc., etc. Anything bad that can happen in the future is risk.
When money is paid up front, you load that risk on the organization. When you load that money differently, you distribute that risk to the player.
Let's say you have a guy you can pay $1m to build a house. You can pay it all to him on Tuesday, then try to enforce the contract; or, you can hold the $1m until the house is built to your satisfaction. Which do you do? Load the risk on the contractor, to incentivize performance.
That's one basic tension involved in these contracts. Everybody wants the risk loaded onto the other guy... and paying up front for medium talent-level, unknown long-term motivation guys (front-loading risk,) is much less appealing than in the Seymour or Brady cases (high reward is much more established.)
Hope I'm neither overemphasizing the risk-management aspect out of my own idle speculation, or on the other hand, stating the obvious too very much.
PFnV