There's no set formula for how NFL contracts are constructed, but since the Lions aren't in a position to front-load a deal, here's a hypothetical projection.
YEAR BASE BONUS CARRYOVER CAP HIT DEAD
2015 $5,000,000 $3,000,000 $9,737,500 $17,737,500 $59,737,500
2016 $15,000,000 $3,000,000 $0 $18,000,000 $42,000,000
2017 $17,000,000 $3,000,000 $0 $20,000,000 $26,000,000
2018 $15,000,000 $3,000,000 $0 $18,000,000 $6,000,000
2019 $16,000,000 $3,000,000 $0 $19,000,000 $3,000,000
2020 $18,000,000 $0 $0 $18,000,000 $0
This hypothetical includes a $15 million signing bonus, spread over the first five years of the contract, as well as the first two years base salaries guaranteed, with the third year being guaranteed on the fifth day of that league year.
The base salary would be lower the first season to compensate for the $9.7 million cap hit carryover stemming from multiple restructures of Suh's previous contract. Still, the 2015 cap hit would be significantly lower (essentially half) what it would take to franchise him.
Much like Watt and McCoy's deals, the team would be in position to move on after three seasons if production no longer matched salary.
I know this is just a guess......but that would be a very good deal for the Lions. Basically a 3 or 4 year deal but structured in a way that would allow an out if he does fall off or get injured.
After 3 years.......if everything went to hell....you could be out of Suh's, Staffords and Calvins contracts with minimal dead cap money.