The signing makes sense given that the Rams allowed safety O.J. Atogwe to leave the team after the 2010 season to sign with the Washington Redskins.
Atogwe was a team captain and a key piece to the defense, so the Rams would be facing a major void this season had they not found a replacement.
The 30-year-old Mikell was a second-team All Pro in both 2008 and 2010, and he was voted to the Pro Bowl in 2010.
He is solid in pass coverage, deflecting 28 passed in 2010 and 2009 combined, and he is also a capable tackler—he had over 90 tackles in both 2008 (93) and 2009 (90), as well as 88 tackles in 2010.
Mikell will be an immediate starter, and he'll likely be an improvement over Atogwe.
He'll start alongside either James Bulter, or Craig Dahl.