All teams faced a midnight ET deadline on Friday to set their rosters in preparation for the Rule 5 Draft, which will take place next month at the Winter Meetings in Dallas. The Nats' roster now is at 37 players.
On Friday, the Nationals selected the contracts of first baseman Tyler Moore, catchers Derek Norris and Jhonatan Solano, and outfielder Eury Perez. They also reclaimed right-hander Cole Kimball off waivers from the Blue Jays.
The series of moves was announced by Nats executive vice president of baseball operations and general manager Mike Rizzo.
Two days after he was claimed by the Blue Jays, the Nationals reclaimed Kimball, ranked the Nats' ninth-best prospect by MLB.com, off waivers.
The Blue Jays, creating roster room for right-hander Andrew Carpenter, placed Kimball on waivers. Before Kimball could clear waivers and be outrighted to Triple-A, the Nationals claimed the reliever and placed him on their 40-man roster.
In July, Kimball had surgery to repair a torn rotator cuff in his right shoulder. He is expected to miss much of the first half of the season. Kimball, 26, was 1-0 with a 1.93 ERA in 12 relief appearances with the Nationals.
At Double-A Harrisburg, Moore hit .271 with 35 doubles, 31 home runs and 90 RBIs in 137 games. The 24-year-old paced the Eastern League in home runs, RBIs and total bases (276).
In the past two years, Moore has 202 RBIs. He was the Nationals' 2010 Minor League Player of the Year.
Also at Harrisburg, Norris belted 20 home runs, collected 46 RBIs, and he had a .367 on-base percentage.
Solano had a solid season at Triple-A Syracuse in the International League, batting .275 with 14 doubles, five home runs and 33 RBIs in 78 games.
Perez, 21, the sixth-best Nats prospect according to MLB.com, batted .283 with nine doubles, two triples, one home run and 41 RBIs at Class A Potomac.