Earlier this season the finest wide receiver in franchise history, Rod Smith, retired.

Soon, the finest center in franchise history, Tom Nalen, could be doing the same.

The Broncos placed Nalen on the season-ending injured-reserve list Tuesday with a left knee injury, marking the unofficial end of an era.

Nalen excelled at center for 15 years, during which time he started 188 games and went to five Pro Bowls — not bad for a seventh-round pick in the 1994 draft.

Nalen probably will not make the Pro Football Hall of Fame, though he is worthy. He will make the Broncos Ring of Fame. And he was, undeniably, one of the finest centers to ever play the game.

He still could try to return next season, but the odds are against him. Then again, they were against a seventh-round pick making it as far as Nalen did.