Ohlman won the Carolina League batting title, hitting .313/.410/.524 in 100 games for Frederick, including 13 homers and 53 RBIs. He was ranked as the O's 19th-best prospect to start the year, but his standing in the organization has grown considerably.
The 28-year-old Gamboa is the most surprising name of the three. In nine starts for Triple-A Norfolk, his first season as a knuckler, he went 2-5 with a 6.23 ERA.
The Orioles now have 36 players on the 40-man roster.
Players first signed at age 18 must be added to 40-man rosters within five seasons or they become eligible to be taken by other organizations through the Rule 5 Draft. Players signed at 19 or older have to be protected within four seasons. So highly regarded pitchers like Eduardo Rodriguez and Mike Wright, for example, don't need to be protected just yet.
For eligible players left off, clubs pay $50,000 to select someone in the Major League phase of the Rule 5 Draft, slated to take place on Thursday, Dec. 12. If that player doesn't stay on the 25-man roster for the full season, he must be offered back to his former team for $25,000.
In other words, an international player or high school draftee signed in 2009, assuming he was 18 or younger as of June 5 of that year, must be protected. A college player taken in the 2010 Draft is in the same boat.
The Orioles have taken a player in the Major League portion of the Rule 5 Draft the past two years and were able to keep him on the roster for the entire season. As a result, both infielder Ryan Flaherty and left-handed pitcher T.J. McFarland are now in the organization.
Brittany Ghiroli is a reporter for MLB.com. Read her blog, Britt's Bird Watch, and follow her on Twitter @britt_ghiroli. This story was not subject to the approval of Major League Baseball or its clubs.