The Seahawks have signed offensive lineman Bradley Sowell. The reported deal is worth $1.5M for one year, and I'd be pretty surprised it's all guaranteed. Sowell has been a member of the Arizona Cardinals the past three seasons, but hasn't made a start since 2013, where he took over for a traded Levi Brown, and played left tackle for 12 games. He "graded out dreadfully in pass protection and in run blocking" at left tackle that year, per Revenge of the Birds.
The 6'7, 312 pound tackle is in his fifth season out of Ole Miss, and could be viewed by the Seahawks' brass as a potential swing tackle or guard prospect. If I had to guess, he's this year's version of Eric Winston, or in other words, a draft hedge veteran with some experience that could play a starter or reserve role if no one from the draft class beats him out for a job. Back in 2014, Eric Winston was signed under pretty much the same circumstances but was ultimately released when Justin Britt won the right tackle job. In other words, this is not a splash move meant to solve the Seahawks' woes on the offensive line.
For what it's worth, Sowell was also one of the Cardinals' emergency long-snappers, so there is a tiny bit of value there as well.
This is Seattle's first move in outside free agency. I'm guessing he's the first of a few moves the team will make.