Carpenter, a sixth-year veteran and former first-round pick, spent the spring and summer with the Patriots before being released on Sept. 1. He played in all 16 games with three starts for the Lions last season and had 29 tackles and an interception-return touchdown. Carpenter provides insurance at linebacker, as starter Dont'a Hightower was injured in Week Four.
The Patriots signed McClain on Sept. 26 and he appeared in Sunday’s win over Buffalo in a reserve role. McClain was a third-round pick of the Panthers in 2011.
The Patriots also signed TE Alex Silvestro to their practice squad and released OL Thomas Austin.