49ers taking a look at defensive tackle Earl Mitchell

SANTA CLARA, Calif. -- The NFL free-agent market doesn't open officially until March 9 with teams able to begin negotiating with players on March 7. Before we get to that time, though, teams are already in the process of releasing players to create salary-cap space.

Players who do get cut in the run-up to free agency don't have to wait to sign with another team, which means there's already a market of sorts developing. And the San Francisco 49ers are among the teams dipping their toes into those waters.

Miami released defensive tackle Earl Mitchell on Feb. 16, but it didn't take long for suitors to begin pursuing Mitchell. He visited Seattle on Monday and was to visit the 49ers on Tuesday.

Mitchell, on Wednesday, is scheduled to visit Denver and coach Vance Joseph, who was his defensive coordinator in Miami last season. He is scheduled to visit Atlanta later this week. The NFL Network first reported Mitchell's tour of teams over the weekend.

For the 49ers, Mitchell would make sense as a possible addition to their defensive line rotation. Under new defensive coordinator Robert Saleh, they are expected to transition to a 4-3 base defense. Though the 49ers have some defensive linemen in place, they are in the market for a run-stuffer after having the worst run defense in the league last season.

That's a role Mitchell could help fill, though he probably wouldn't be the only addition San Francisco would look to make upfront. The 6-foot-3, 310-pound Mitchell played 292 snaps in nine games with 18 tackles in 2016. In 100 games, he has 207 tackles, 5.5 sacks and a forced fumble while averaging 27.4 snaps per game.

With defensive tackle Glenn Dorsey set to become an unrestricted free agent, the 49ers are in need of a nose tackle capable of playing the zero or one-technique in their new-look defensive system. Mitchell also has some ties to the 49ers' new coaching staff, having played for new defensive line coach Jeff Zgonina when he was the assistant defensive line coach for Houston in 2013.