The Seahawks will not be able to officially sign Cary Williams until the NFL Free Agency period starts at 1PT, but per Aaron Wilson, here are the details of the deal:
Williams will get:
$3.5M signing bonus
2015 Base Salary of $3.5m
2016 Base Salary of $5M
2017 Base Salary of $6M
$7M is guaranteed, meaning none of his 2016 money is guaranteed.
Cap Hits would look like this
If the Seahawks cut Cary Williams before the 2016 they could take a cap charge of $2.33M, but would get a net savings of $3.83M for 2016.
If they designated Cary Williams a post June 1 designation in 2016, they could split that dead cap charge over two years.
I believe Seahawks will draft and develop two corners in 2015, but this gives them a veteran stop gap for one year.
As for Will Blackmon, he got a much more modest contract -- per Aaron Wilson, Blackmon's contract is for one year and $950,000, with $870,00 in salary and an $80,000 bonus.