WASHINGTON -- The Nationals made an early summer splash on Monday evening, acquiring right-handed closer Kelvin Herrera from the Royals in exchange for a trio of Minor Leaguers: infielder Kelvin Gutierrez, outfielder Blake Perkins and right-hander Yohanse Morel. The trade helps bolster Washington's bullpen, which has become something of a midsummer tradition, by adding another reliever with experience pitching in high-leverage and big-game situations.