Source: Josh Alper, NBC Sports 
Casillas signed with the Bucs as a free agent before the season and had played in all 12 games for the team this season. He started four of those games, including the Week 13 loss to the Panthers that he couldn’t finish because he hurt his knee. Casillas finishes the year with 24 tackles and a forced fumble on defense as well as a team-high nine tackles in kick coverage.
The Bucs could turn to Dekoda Watson, Adam Hayward or Ka’Lial Glaud on the strong side of their defense with Casillas out of the lineup.