Zimmermann cleared waivers Saturday and was sent outright to Triple-A Norfolk, Jake Rill of MLB.com reports.

The Orioles designated Zimmermann for assignment Thursday.

Zimmermann (hamstring) allowed a run on two hits and two walks while striking out four over three innings for Triple-A Norfolk in its game versus Durham on Wednesday.

Triple-A Norfolk placed Zimmermann on its 7-day injured list Sunday with a hamstring injury, Rich Dubroff of BaltimoreBaseball.com reports.

The Orioles optioned Zimmermann to Triple-A Norfolk on Tuesday, Jake Rill of MLB.com reports.

Zimmermann has allowed five runs (three earned) on 12 hits and three walks with seven strikeouts over 7.2 innings in Grapefruit League play.

Zimmermann could be in the mix for a rotation spot with John Means (elbow) and Kyle Bradish (elbow) likely to miss the start of the season, Roch Kubatko of MASNSports.com reports.

Zimmermann (abdomen) said he should be a "full go" for spring training, Steve Melewski of MASNSports.com reports.

Zimmermann underwent core muscle surgery Thursday, Roch Kubatko of MASNSports.com reports.

Zimmermann was optioned to Triple-A Norfolk on Sunday.