Finnegan was optioned to Double-A Harrisburg on Thursday, Jesse Dougherty of The Washington Post reports.
Finnegan was in the mix for one of the team's final bullpen spots but failed to seize the opportunity, posting a 5.40 ERA and 3:3 K:BB through five innings before spring training was suspended. The right-hander figures to make his big-league debut in 2020 if he continues to impress in the upper minors.