Knowing starting tight end Heath Miller might not be ready by the beginning of the 2013 NFL season, the Pittsburgh Steelers were proactive in free-agency landing insurance policies and former castaways Matt Spaeth and David Johnson. Johnson's policy is on the verge of being cancelled.

No wonder David Johnson looks so bad walking. Underwent another knee sugery last Friday. 2 week recovery. — James C Wexell (@jimwexell) July 31, 2013

Johnson was competing with Spaeth and sophomore David Paulson for roster spots, knowing Miller's could be available at least for a little while. Johnson however has spent all of camp on the PUP list with Miller, and now we know why.

The Steelers already replaced an injured Zach Pianalto with a healthy Peter Tuitupou, and signed John Rabe to fill in during drills as they await Johnson's recovery. Jamie McCoy continues to look like the team's practice squad tight end. While Spaeth and Paulson have shined at moments in Johnson's absence, but Tuitupou and Rabe have not.

If Johnson's procedure fixed the issue with the same knee which required surgery to repair a torn ACL following the first preseason game of 2012, he should still have a chance to earn the third TE spot until Miller returns. If it didn't, he may wind up unemployed once again.

Rookie defensive end Nick Williams missed Wednesday's practice with a knee injury. Cornerback Cortez Allen was held out again with the same knee injury that cost him Monday's practice. DeMarcus Van Dyke's hamstring injury could hold him out for "a while," Steelers coach Mike Tomlin said, according to Post Gazette reporter Ed Bouchette.

Terry Hawthorne (knee) missed Wednesday's practice as well.

More from Behind the Steel Curtain: