49ers rookie linebacker Reuben Foster is set to miss some time after spraining his ankle in the season opener against the Panthers and that may lead the team to add a new player at the position to help fill the gap.
Butler played 14 games for the Dolphins last year, starting five times and recording 28 tackles. He did not sign with anyone this offseason.
Spence did sign with the Colts in March, but failed to make the team’s cut to 53 players earlier this month. He had 54 tackles, three sacks and a forced fumble in 15 appearances for the Titans last season.
Foster moved into the starting lineup this summer when Malcolm Smith was lost for the year with a torn pectoral muscle. That left Ray Ray Armstrong to take over for Foster when he was injured against Carolina.