No one knows exactly how the Minnesota Vikings' quarterback situation will play out in free agency, where the team could lose all three of the veterans who took snaps at the position in 2018.

That apparently includes head coach Mike Zimmer, who cast doubt on two of those three quarterbacks' future in Minnesota on Thursday.

A week after NFL Network's Tom Pelissero reported that Week 1 starter Sam Bradford "absolutely intends to play in 2018" after a November knee surgery revealed that the quarterback's infamous ligaments were "intact," Zimmer told media at the scouting combine that Bradford has a "degenerative" knee.

That's hardly a ringing endorsement of the veteran's health entering free agency, although Zimmer, per Pelissero, also said "Bradford was skiing last week," so "getting through a full season is the real unknown" -- and the factor that figures to force the former No 1 overall draft pick and 2016 trade acquisition to a new home in the coming weeks.

In regards to Case Keenum, the man who replaced an injured Bradford and led the Vikings to the NFC Championship Game but is also set to hit free agency, Zimmer wasn't any more convinced.