In Harper, the Nationals add a serviceable right-handed reliever who made his big-league debut last season and wound up making 61 appearances (3.81 ERA). He turns 31 in late March and stands a good shot at breaking camp with the Nats after spring training.

The Twins designated Harper for assignment recently in order to add new third baseman Josh Donaldson to the 40-man roster. So, they shipped him to D.C. in exchange for McMahon (who was a ninth-round draft pick in '19). The 21-year-old has some upside.

Harper could become a setup man in Washington but he is not worthy of being drafted in most league formats at this point. Keep an eye on his progress in spring training to see whether he might become an in-season pickup option. As for McMahon, he is still a few years away from being on the fantasy radar.