Thomas, 29, was signed by Seattle in July after spending the previous six seasons with the New York Giants. After missing 2011 and 2012 due to ACL injuries, Thomas returned last season to play in all 16 games and start seven, tallying 67 combined tackles and one interception. He played for Seahawks coach Pete Carroll at USC.
Jeffcoat was signed by the team in May after he wasn't selected in the 2014 NFL draft despite a successful college career at Texas that saw Jeffcoat earn First Team All-American honors as a senior. Team were concerned that he was a tweener between defensive end and linebacker, and after spending the bulk of his career with the Longhorns at end, he was moved to linebacker by the Seahawks.
If Jeffcoat clears waivers, he can be placed on Seattle's practice squad, the size of which league-wide has increased to 10 players per a rule change announced by the NFL last week.
Teams have to cut their rosters to 75 players by 4 p.m. ET on Tuesday. Seattle's roster stands at 88 after these two moves.
- Ben Estes