Brock joined the Niners as an undrafted rookie in 2010. In two seasons, he has 14 tackles and two interceptions.
Grant was a seventh-rounder in 2008 and rejoined the 49ers in 2011 after three seasons with the Rams. He made 30 tackles and two sacks last season. In a start on "Monday Night Football" against the Steelers, Grant had five tackles and four passes defnesed.