It turns out that Roc Carmichael wasn't the only defensive back who worked out for the Detroit Lions on Wednesday. According to Howard Balzer, the Lions also worked out cornerback Tommie Campbell and safeties Anthony Walters and Chris Clemons.
Clemons is by far the most notable player among that group. He actually took a free-agent visit with the Lions back in March. For a while, it looked like they might sign him to replace Louis Delmas, but the Lions instead went with James Ihedigbo a few days later. Clemons, who played for the Miami Dolphins from 2009-13, ended up signing with the Houston Texans, but he was let go during the final round of cuts.
Campbell and Walters were also let go during the final round of cuts. Campbell was released by the Tennessee Titans after spending three seasons with the team, and Walters was let go by the Arizona Cardinals after originally joining the team in May. Previously, Walters played for the Chicago Bears from 2011-13.
In all likelihood, the Lions were simply doing their due diligence on potential options in the secondary in case they need help at cornerback or safety down the road. Clemons does seem like he would be a nice addition at safety, especially if Ihedigbo and Don Carey continue to miss time, but none of these players will likely be candidates to be signed until Week 2 at the earliest.