the-commish

It's not loopholes. The signing bonus is pro-rated over the term of the contract. For instance, a $24 million signing bonus over a 6-year contract comes out to $4 million per year. To that is added each year's salary, plus any incentives, to come up with that season's cap hit. For instance, in Graham's case (we don't know any actual numbers yet except for the $7.053 million franchise tag for this season, which counts against the Saints' salary cap). So if Graham get $24 million in signing bonus, and a $2 million dollar salary for 2014, that adds up to $6 million against the cap for 2014 (if no incentives). In that case, the Saints would gain $1.053 million in this season's cap (the difference between the $7.053 million franchise tag and the $6 million pro-rated bonus + 2014 salary.

The signing bonus portion is guaranteed. If that player were to be waived before the end of the contract, the remaining portion of the pro-rated signing bonus would count against the salary cap... which is then "dead money." In some cases the cap hit can be spread over two seasons (I don't know the exact details of how this is done). Perhaps someone can post to this subject.