Michael Conroy/Associated Press

Marlon Mack had a quality rookie season with the Indianapolis Colts, which was even more impressive after discovering he played the entire year with a serious injury.

General manager Chris Ballard told SiriusXM NFL Radio Tuesday that the running back played the entire year with a torn labrum (h/t Pro Football Talk's Charean Williams). Mack has since undergone offseason surgery to repair the issue and is expected to be 100 percent by the start of training camp.

The 2017 fourth-round pick worked as a change-of-pace back behind Frank Gore last season and was seemingly the more dynamic player whenever he had the ball.

He finished the year with 358 rushing yards, 225 receiving yards and four total touchdowns.

With Gore signing with the Miami Dolphins this offseason, the depth chart is wide open for Mack to become a featured player, especially if he is healthy.

The Colts did draft Nyheim Hines out of NC State in the fourth round, while Josh Ferguson, Robert Turbin and Christine Michael could all also battle for playing time next season. However, Mack proved last year when he got the opportunity that he can be a valuable asset both as a runner and as a receiver out of the backfield.

After the team ranked just 28th in the NFL in rushing yards per attempt, a healthy Mack will hopefully turn things around in 2018.