Smith, an 11-year pro who signed a three-year contract extension before the 2006 season, was due to make $3.28 million in base salary next season despite his dwindling role on the San Francisco defense. Willis, the NFL's defensive rookie of the year, took over Smith's role as the 49ers' defensive leader and top tackler.
"Derek has been an important member of the 49ers," coach Mike Nolan said. "You don't make these kinds of decisions without battling the emotion that is natural when you are dealing with a player that has done so much for your organization. We made the decision because we have quality linebackers who we think are the future of the 49ers. Derek was a model professional, and he influenced a lot of the younger players with his work ethic."
Smith has long been one of the NFL's top unsung defensive players, annually racking up gaudy tackling statistics with little fanfare. He made at least 123 tackles in each of his first nine NFL seasons -- four with Washington and five with San Francisco, where he has played since signing as a free agent in 2001.
Smith was voted the 49ers' co-MVP in 2005, but missed two games in 2006 because of a strained eye muscle that limited his peripheral vision, eventually requiring surgery. He started 14 games and made 98 tackles last season, but his playing time decreased significantly in the final months of San Francisco's fifth straight losing campaign.