Voth's absence from the Nationals' World Series roster was due to a flare-up of his shoulder tendinitis, Jesse Dougherty of The Washington Post reports.
Voth recorded a 3.30 ERA and a 1.05 WHIP in 43.2 innings for the Nationals last season, but missed over a month in the middle of the season with a shoulder injury, an issue which apparently didn't go away completely. That adds some injury risk for him heading into the 2020 campaign, though he's expected to be ready to go at the start of spring training.