As recently as 2007, center Dan Koppen was a Pro Bowler and an All-Pro, and at the start of 2011, he was on the Patriots' first team. But he never got back his job after suffering a fractured ankle in last year's season opener, which is why he was available to the Broncos.

ESPN first reported that the Broncos will sign the 10-year veteran Koppen, who started 120 games over the last nine seasons in New England. However, he is not expected to simply take the spot on the 53-man roster that will be created when DT Ty Warren goes on injured reserve, because Broncos coach John Fox said that QB Caleb Hanie will be re-signed after being waived Saturday in a "procedural" move.

The addition of Koppen could be interpreted as putting pressure on center J.D. Walton, who has started every game at the position since the Broncos drafted him in 2010. Denver's brief free-agent pursuit of ex-Colts center Jeff Saturday in March offered an indication that the Broncos would rather go in another direction after Peyton Manning's arrival, but when Saturday signed with the Packers, the Broncos went with Walton, and gave him almost all of the first-team work in training camp and offseason practices.

Denver allowed just two sacks to the blitzing Steelers on Sunday night -- one which came when Knowshon Moreno whiffed on blocking Steelers LB Larry Foote, and another when the Steelers overwhelmed one flank of the Broncos' line, leaving Jason Worilds free for a sack.

But the Broncos have also made a habit of signing veteran former starters to provide depth in recent weeks, having added LB Keith Brooking and FS Jim Leonhard during training camp. Both played in the regular-season opener Sunday, but on a limited, situational basis. A similar role could await Koppen with the Broncos.

For up-to-the-minute Broncos updates, follow Andrew Mason on Twitter at @CBSBroncos and @MaxBroncos.