Should be a little less than that depending on how exactly the signing bonus is structured. His base salary for 2017 is just $900K, roster bonus $600K, workout bonus $250K, plus his $6.3 million signing bonus. Cash wise, he made $8.05 million of his $21 million contract. His cap hit this year is only $3.85 million (base, workout, roster money, plus his prorated signing bonus). I doubt his signing bonus is structured so that the Packers can get back $4.2 million of it (some players when they retired, the team actually went to the player to get part of the signing bonus paid back). That's the only portion of his contract that was guaranteed. Meaning, that next season, the Packers have to take a $4.2 million dead cap hit for his unapplied signing bonus.
As for Jimmy Graham, he definitely has not worked out in Seattle. Miscalculation on the part of the Seahawks on their ability to integrate Graham into their offence. He's not a blocker, which is the type of TE that the Hawks offensive scheme calls for.
But, as for the Hawks being able to move him in a deal for a OL, I don't see it happening. Best OL available are Staley, but he still has term on his contract and if SF does draft a QB in the upcoming draft, it would be nice to have a veteran top tier LT to protect his blindside. Brown from Houston, maybe, but don't really see it. Hawks gave up their 2nd rounder in 2018 in the Richardson deal. And a 1st for Brown is too much.
For Seattle and Graham, one thing that teams always consider is the draft pick compensation that they can get for players. You get a comp pick if a player leaves via free agency (but only if their contract has expired, you don't get a comp pick for a player that you cut.) So, depending on who the Hawks sign and let go this off-season, they can get back a 3rd round pick (if Graham signs for $9 million or more per season), or a lower round pick if he signs for less than that.
You saw that with NE and Collins last year. With NE signing Gilmore, that would have wiped out any comp. pick that they would have received if they kept Collins and let him leave via free agency. thus they made the deal with CLE to get a 3rd round pick.
Very few trades are ever made a the deadline. And usually you end up with underperforming guys being dealt for day 3 draft picks.