With Bly, 49ers replace experience with experience

Posted by ESPN.com's Mike Sando

Walt Harris started 16 games and played more than 90 percent of the 49ers' defensive snaps last season. Dre Bly did the same for the Broncos.

It's unclear how much Bly will play for the 49ers after San Francisco reached an agreement with him Thursday following Harris' likely season-ending knee injury. His presence gives the 49ers another experienced cornerback and a potential starter, depending on what Tarell Brown and Shawntae Spencer show this summer.

Bly turns 32 Friday. Harris turns 35 in August. Bly, released by the Broncos in February, has been a full-time starter since 2002. Harris has been a full-time starter since 1996. Bly has fewer miles and more speed. Harris was more experienced and far more versed in the 49ers' defensive system, though Bly will have three full months to learn the defense before San Francisco needs him in a game.