The Lions have had a busy week transactions-wise, having to put one player on injured reserve and signing/releasing a few others. Today is actually already the busiest day of the week so far, as the Lions have made a total of four moves and it's not even noon yet.
Jahi Word-Daniels, the cornerback who was just re-signed on Tuesday, was waived. The sole reason the Lions signed him was to improve depth in a banged up secondary, and he went and got hurt on Tuesday. As a result, the Lions replaced him with cornerback T.J. Rushing, a former Colts player.
The other moves involved kickers. Aaron Pettrey was waived and Steven Hauschka was claimed off waivers from the Falcons. Pettrey is likely being let go because he missed a field goal against the Steelers. I imagine the Lions figured they might as well kick the tires (no pun intended) on someone else with Jason Hanson still out.