The #Seahawks have made a trade, acquiring CB Mohammed Seisay from DET for an undisclosed pick in the 2016 draft.— Brady Henderson (@BradyHenderson) August 2, 2015
Chances are the Lions will get a late-round pick in exchange for Seisay, and it could be of the conditional variety. If that's the case, Seisay might have to actually make the Seahawks' roster or something along the lines of that for the Lions to actually receive a pick back as part of this deal.
In any case, this is an interesting move. Seisay joined the Lions last year as an undrafted free agent out of Nebraska, and he opened the 2014 season on the practice squad. After injuries piled up at cornerback early in the season, Seisay was promoted to the active roster, and he played in 13 games during the regular season.
This year, with players like Alex Carter, Quandre Diggs and Josh Wilson joining the team and Nevin Lawson returning from an injury, Seisay's chances of making the 53-man roster were quite slim. As a result, the Lions decided to go ahead and part ways with him now via a trade in order to get something back in return for him.
UPDATE: The Lions received a sixth-round pick for Seisay, according to Rob Rang.