Traber, who was a swing man for the Nationals, appeared in 28 games and had a 4.76 ERA. He was sent down to the Minor Leagues in early August and stayed with Triple-A Columbus for the rest of the season.
Jones, a childhood friend of third baseman Ryan Zimmerman's, pitched for Class A Hagerstown, Class A Potomac and Double-A Harrisburg. His best work came with Potomac, where he went 7-8 with a 3.96 ERA in 17 games.
While Traber was released because of lack of production, Jones was sent packing because he suffered a serious knee injury while playing basketball and the Nationals didn't want to fill a roster spot with an injured player.
"He really came a long way. We were very proud of what he accomplished," general manager Jim Bowden said about Jones. "He went and played basketball and blew his knee out. He is out for next year and we just made the decision that we wanted to fill our roster spot with a healthy player.
"We have told Justin Jones and his agent that we are interested in signing him to a Minor League contract. We will support him in his rehabilitation. We would like to get him back and get him healthy, but not at the price of a roster spot given what we are trying to do."
By having four roster spots available, according to Bowden, the Nationals will participate in the Rule 5 Draft on Thursday morning and select a player from the Major League phase.
"We spent a lot of time [on Wednesday] going over the Rule 5 Draft, studying a lot of players," Bowden said. "There were a lot of healthy discussions, and I think that it's likely that we will select a player tomorrow in the Rule 5 Draft in the Major League portion."
Bill Ladson is a reporter for MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.