All four pitchers are expected to work out of the bullpen, while Brown and Lombardozzi are expected to come off the bench and get a couple of starts.
Of the seven, Lombardozzi, Brown and Peacock will be in the big leagues for the first time. Severino has been on the Nats' big league roster, but never appeared in a game.
Lombardozzi and Peacock are arguably Washington's best players in the system. Peacock, who was the Eastern League Pitcher of the Year, went a combined 15-3 with a 2.39 ERA for Syracuse and Double-A Harrisburg. He also struck out 177 in 146 2/3 innings.
Lombardozzi may be the leadoff hitter the Nationals are looking for. In 134 games, Lombardozzi hit .309 with eight home runs, 52 RBIs and a .360 on-base percentage.