"You set your roster and you are always taking chances on losing any of your prospects," assistant general manager Bryan Minniti said. "You wish them well, you wish them luck. You hope to get them back at some point in the next year and don't lose them totally."
Of all the players the Nats lost, Kobernus was the biggest surprise. He was selected by the Red Sox in the Major League phase of the Draft and was later traded to the Tigers. The Tigers are expecting him to be a utility infielder.
Last season, Kobernus played for Double-A Harrisburg, hitting .282 with one home run and 19 RBIs.
"We're not drafting him to be a starter for us," Tigers general manager Dave Dombrowski said. "We're drafting him to be a utility guy. And if you're going to play second base, you're not going to just make it as a utility guy like that. So he'd have to compete to be able to play some other positions. We think he has the athleticism to do that. He was a high Draft choice."
McGeary, who was taken by the Red Sox in the Minor League phase, was selected by Washington in the sixth round of the 2007 First-Year Player Draft. McGeary received a $1.8 million signing bonus, and the team paid for his college education to Stanford University.
However, McGeary was never able to find consistency on the mound. It didn't help that he had Tommy John surgery in 2010. This past season, he made eight relief appearances and allowed a combined seven runs in 9 1/3 innings between Class A Auburn and the Gulf Coast Nationals.
Rosenbaum was taken by the Rockies in the Major League phase of the Draft. He pitched the entire 2012 season with Double-A Harrisburg, leading the team in wins with eight and posting a 3.94 ERA. Even more impressive, Rosenbaum walked just 39 batters in 155 1/3 innings.
Nelo was selected by the Dodgers in the Minor League phase of the Draft. A late-inning reliever, Nelo saved 16 games, had a 2.73 ERA and struck out 63 batters in 52 2/3 innings.
The Nats were expected to lose outfielder Destin Hood in the Draft, but he was bypassed. Hood, a highly touted prospect two years ago, struggled this past season, hitting .245 with three home runs and 45 RBIs.
"He is a corner outfielder at Double-A," Minniti said. "That's tough to hide in the big leagues if he is not prepared to contribute right away. He did come on later in the year."
Bill Ladson is a reporter for MLB.com and writes an MLBlog, All Nats All the time. He also could be found on Twitter @WashingNats. This story was not subject to the approval of Major League Baseball or its clubs.