The Nats had been looking for catching depth, and Seabury is known for his defensive abilities.
"We had some scouting reports on him," general manager Mike Rizzo said. "You can never have enough catching depth. He will come into Minor League camp and try to back up one of our prospects."
Buschmann is a swing man who had one of his worst seasons in 2011, going a combined 12-6 with a 6.16 ERA for Double-A San Antonio and Triple-A Tucson.
In the Major League phase of the Draft, the Nationals lost outfielder Erik Komatsu to the Cardinals and right-hander Brad Meyers to the Yankees.
Komatsu was acquired last July in the trade that sent infielder/outfielder Jerry Hairston Jr. to the Brewers. Komatsu was Milwaukee's Minor League Player of the Year in 2010, when he hit .323 with five home runs and 63 RBIs for Class A Advanced Brevard County. He is projected to play center field and become a leadoff hitter.
This year, prior to the trade, Komatsu played for Double-A Huntsville, hitting .294 with six home runs, 40 RBIs and a .393 on-base percentage. After the trade, Komatsu was assigned to Double-A Harrisburg and hit .234 with a home run and eight RBIs.
"We feel that with the crop of guys that we have moving up, they would push Komatsu, and we felt we had enough depth to leave him exposed," Rizzo said.
Meyers was Washington's Minor League Pitcher of the Year in 2009 but was never given a chance to pitch in the big leagues.
"We felt we had enough depth if we lose a starting pitcher or two," Rizzo said. "We actually anticipated losing more than one starter in the Major League phase of the Rule 5 Draft. It goes with the territory. When you build a Minor League system -- and the farm system is getting better -- it often happens that you lose a player, because you just can't protect everybody."
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.