Locke, who attended UCLA, was initially a fifth-round draft pick by the Minnesota Vikings in 2013. In four seasons with Minnesota (2013-16), he appeared in 64 games while registering 290 punts for 12,535 yards (43.2 average), a 38.7 net average, and 101 punts downed inside the 20-yard line, according to the 49ers Communications department.
Locke signed with the Indianapolis Colts on March 10, 2017, but was released on August 28, 2017. He signed with the Detroit Lions on September 12, 2017, where he appeared in five games and punted 27 times for 1,222 yards (45.3 average), a net average of 42.2, and 11 punts downed inside the 20-yard line before his release on October 24, 2017.
The 49ers tendered a one-year contract to Mostert, who was an exclusive rights free agent, on March 9. The running back appeared in each of the 49ers' first 11 games of the 2017 season and carried the football six times for 30 yards. Mostert also added a team-high eight tackles on special teams. He originally joined the 49ers after being signed to the team's practice squad on November 28, 2016.
Mostert entered the NFL as an undrafted free agent with the Philadelphia Eagles in 2015 and has appeared in games with the Miami Dolphins, Baltimore Ravens, Cleveland Browns, and Chicago Bears.