Washington's roster is now at 32.
The Nationals selected Whitney in the Rule 5 Draft last December in hopes that he could be a power hitter off the bench, but the Nationals already have enough quality reserves on their roster.
This spring, Whitney went 3-for-28 (.107) with a homer and six RBIs. The Nationals will get back half of the $50,000 they spent for selecting Whitney in the Rule 5 Draft.
O'Connor got off to a good start this spring, but was hit hard against the Mets on Monday. O'Connor didn't have command of his pitches. In fact, he threw 85 pitches in 4 2/3 innings and only 10 first-pitch strikes.
Bill Ladson is a reporter for MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.