Hafner went 4-1-0 with Colorado during 2016-17 regular season season, posting a 2.62 goals-against average and a .926 save percentage. The 25-year-old went on to win an ECHL-best 14 games in the postseason, going 14-2 with a 2.43 goals-against average and helping lead the Eagles to a Kelly Cup championship.
Hafner was signed by Colorado last February after beginning the 2016-17 season with the Columbus Cottonmouths of the Southern Professional Hockey League, where he assembled a record of 4-2-0 to compliment a 2.01 goals-against average and a .935 save percentage. The Toledo, Ohio native also appeared in five contests for the Alaska Aces, going 3-0-2 while notching a 2.13 goals-against average.
Hafner spent four seasons at Western Michigan University, highlighted by a junior season in which he played 21 games for the Broncos, finishing the season with a 2.06 goals-against average and a .925 save percentage, including a pair of shutouts.