On December 19, 2014, the Padres traded Ross and a player to be named later, Trea Turner, to the Washington Nationals as part of a three-team trade, in which the Padres traded Jake Bauers, Burch Smith, and René Rivera to the Tampa Bay Rays, and Washington traded Steven Souza and Travis Ott to Tampa Bay. On June 6, 2015, Ross was called up to the majors for the first time and he made his major league debut that day as a starting pitcher. Ross outdueled Jimmy Nelson and A. J. Burnett in his second and third starts, respectively, earning wins for the Washington Nationals. He struck out 11 batters in his third appearance, snapping an eight-game winning streak by the Pittsburgh Pirates. On August 6, manager Matt Williams announced Ross would remain in the rotation and veteran starter Doug Fister would move to the bullpen, in recognition of the rookie's strong performance since his promotion. Ross' promotion lasted barely a month before Williams said on September 8 that reliever Tanner Roark would take over his spot in the rotation and Ross would move to the bullpen in an effort to keep him from exceeding an undisclosed "innings limit" for the season. Although Ross started the 2016 season in the Nationals' rotation, he lost much of the season due to right shoulder inflammation. He was placed on the disabled list on July 3, 2016, and was activated again on September 18. Upon returning from the disabled list, Ross struggled to pitch deep into games, more than once forming a tandem with rookie right-hander Reynaldo López to pitch the first few innings of a game before López took over in long relief. Ross started game 4 of the 2016 NLDS with the Nats up 2-1 in the series giving up 4 runs on 55 pitches in 2.2 innings. Ross was an up-and-down contributor for the Nationals in the first half of the 2017 season. He started the year pitching for the Class-AAA Syracuse Chiefs, but after Nationals starter Jeremy Guthrie was shelled for 10 earned runs in less than an inning in what would be his only appearance of the season, Ross was called up. Upon struggling in the early going, he was optioned back to Syracuse on May 1 in favor of Jacob Turner. Ross returned to the major league rotation on May 23, pitching well against the Seattle Mariners. Through the first half of the season, Ross received more run support than any other pitcher in the major leagues, with the Nationals averaging more than 10 runs in games Ross started. Out of 13 starts by Ross at the major league level in 2017, the Nationals scored at least 10 runs in eight of them. However, in the last of these starts, against the Atlanta Braves on July 9, Ross exited in the fourth inning as the velocity of his fastball dipped so low into the mid-80s that the stadium radar gun was registering them as changeups. On July 15, 2017, medical tests confirmed that his elbow was diagnosed with a torn ulnar collateral ligament. It was further announced that he would undergo ulnar collateral ligament reconstruction surgery, ruling him out for the remainder of the season and at least part of the 2018 season. In 2017 he was 5-3 with a 5.01 ERA. After recovering from his surgery, Ross attempted to make his first MLB start in 14 months on September 7, 2018, facing the Chicago Cubs on a rainy evening at Nationals Park. The game began after a 1-hour 21-minute delay, but the teams played for only 23 minutes before the game was stopped again with two outs in the top of the second inning and the score tied 0–0. Another 2-hour 54-minute delay ensued before the game was postponed. In his -inning outing, Ross threw 24 pitches, gave up one single and hit one batter, but retired the other five Cubs he faced, and his fastball was clocked consistently at 95 to 96 mph, occasionally reaching 97 mph, which was better than his pre-surgery velocity. In 2018 in three games he was 0-2 with a 5.06 ERA. In 2019 he was 4-4 with a 5.48 ERA. Ross started game 5 of the 2019 World Series for the Nationals in place of Max Scherzer, who was dealing with a back injury. He allowed 4 runs in 5 innings and was credited with the loss as the Astros won 7-1. Ross received a World Series ring for his efforts after the Nationals defeated the Astros in 7 games. On June 29, 2020, Ross announced he would not play in the shortened 2020 season during the COVID-19 pandemic.
Personal life
Ross has an older brother, Tyson Ross, who pitches in MLB. His father is a pediatrician and his mother an emergency room nurse in Oakland. His sister, Frankie, played soccer at Portland State University.
