FOXBORO, Mass. -- Devin McCourty's return to New England Patriots practice was overshadowed by three conspicuous absences.

Quarterback Tom Brady, tight end Rob Gronkowski and center Bryan Stork weren't spotted at the beginning of Friday's Patriots practice. Linebackers Jonathan Freeny (hand) and Eric Martin (illness) also were absent.

It's unclear what kept Brady, Gronkowski and Stork out of practice. Brady and Stork don't have any known injuries. Gronkowski was a full participant in practice Wednesday and Thursday.

McCourty returned after missing two practices with an ankle injury.

Thumbnail photo via Winslow Townson-USA TODAY Sports