Braymer and Kieboom represent the Nationals for the Salt River Rafters, who begin play Monday at 9-7 in first place in the East Division. Hitting coach Luis Ordaz will continue those duties with the East Division team.
Braymer, 24, is 1-0 with a 7.50 ERA, but has allowed only one earned run in four of his five appearances. He went 9-3 with a 2.28 ERA combined for teams in the Nats farm system this season, with 93 strikeouts and only 29 walks in 89 innings.
Kieboom, 21, is batting .270 in 11 games with one triple, one homer, three RBIs, four stolen bases and 11 runs. Carter - brother of Nats catcher Spencer Kieboom - hit .280 this season with 31 doubles, one triple, 16 homers and 69 RBIs. He has played second base in at least one game per week after playing shortstop his whole career. He also has had seven hits and five runs scored in his last three games.
Nationals outfielder Victor Robles won Fall Stars MVP honors last season when he went 1-for-3 with a walk, two runs scored and an RBI, helping lift his team to a 4-2 win. Other notable Nats who have been selected for the Fall Stars contest early in their careers include Anthony Rendon, Derek Norris, Drew Storen, Stephen Strasburg and Bryce Harper.