Interesting read, Mathis may not get as much as he wanted.
http://www.nj.com/giants/index.ssf/2015/06/whats_evan_mathis_worth_on_the_open_market_exec_ag.html
...I asked for some opinions and had three sources guestimate what Mathis would land on the open market. The three-man anonymous panel consisted of a front-office executive, a salary cap expert and an agent.
Executive: 1 year, $3-3.5 million with incentives to reach $5 million
Salary Cap Expert: 3 years, $14-17 million with $6-8 million guaranteed
Agent: 1 year, $3-4 million with incentives to reach $5.5 million