Former Nebraska quarterback Tommy Armstrong tried his hand at safety for 13 practices, but the Vikings had seen enough.
Armstrong was waived Friday, the first day of a five-week break after the Vikings closed the offseason program with a mandatory minicamp at Winter Park.
The 23-year-old Armstrong earned a contract after trying out at both quarterback and safety during the Vikings' rookie minicamp last month.
"You can see some of the traits we look for in defensive players," head coach Mike Zimmer said of Armstrong earlier this month. "Obviously he is still trying to learn some of the basic techniques of things and that will take a while, but he is a good, quality kid to work with."
Armstrong wasn't the only position convert in the Vikings secondary. Former Hopkins standout receiver Terrell Sinkfield re-signed with the Vikings this offseason as a cornerback, and the coaching staff also moved seventh-round pick Jack Tocho from cornerback to safety.
Tocho is joined by five other safeties on the roster in Harrison Smith, Andrew Sendejo, Anthony Harris, Jayron Kearse and Antone Exum Jr.
The Vikings now have an open roster spot.