I would propose in week 8.
LT Bradley Sowell
2017 1st round Pick
2019 Conditional 1st round pick - Conditional on the Seahawks winning a Superbowl in '16, '17, or '18. If not it reverts to a 3rd round pick.
Bradley Sowell gives them a stop gap LT for the rest of the year, another 1st round pick to hasten their rebuild, and a good chance at another 1st rounder, at worst they get another 3rd rounder.
Seattle gets a premier LT in his thirties, at an affordable price for the next 2.5 years. 2016 -$5.18M, 2017 -$10M, 2018 -$10M.
THE BIG POINT
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If Seattle is going to spend a 1st rounder on a LT in the upcoming draft, you might as well spend it now on a known quantity in Joe Thomas. A 1st round LT in 2017 can't help you now, and there is no guarantee a rookie will be any good anyway. (See Tom Cable, and his track record with Offensive Tackles.)
As an additional note, and why it makes a lot of sense is Seattle has no major free agents in 2017 to spend cap on. C-Mike, Luke Willson, and the Kicker are their big Free Agents. Mike B, & Kam may get extensions this upcoming off-season, but that will lead to them having lower cap numbers in 2017, or at worst the same.
This is not a move that only helps the Seahawks for the rest of this year, but for the next 2.5 years. ('16-'17-'18.)
BOTTOM LINE
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This move fits under the salary cap. The only question is the Browns may be asking for a king's ransom, and Seattle are weighing / thinking they might be able to get away with Sowell at LT, and still win a Superbowl.
