4. Patrick Corbin 2019-Present
Many may disagree with Patrick Corbin being on this list due to his sudden decline, but his 2019 season was instrumental in Washington winning their first-ever World Series title. The lefty was signed to a six-year deal worth $140 million at the start of the 2019 season. In his first season with the Nats, Corbin went 14-7, with a 3.25 ERA, 238 strikeouts, and a 3.49 FIP.
Corbin will always be remembered for his 2019 playoff heroics. That year, the Nationals bullpen was one of the worst in the league, and outside of Daniel Hudson and Sean Doolittle, they lacked any constancy. Despite having 0 relief appearances in the Majors, Corbin helped pick up the slack in the post-season, making five trips out of the bullpen.
Most notably, he came out of relief in Games 5 and 7 of the NLDS and World Series respectively. Against the Dodgers in the NLDS, he threw 1 1/3 shutout innings while striking out three. In the World Series, he entered Game Seven with the Nats trailing. He was able to hold Houston at bay, throwing three scoreless innings while striking out three.
Since his World Series heroics, Corbin has been on a steady decline, but his 2019 season alone puts him on this list.
3. Gio Gonzalez 2012-2018
Acquired in a 2012 trade with the Oakland Athletics, Gio Gonzalez helped bolster the Nationals starting rotation. At the time of the trade, Gonzalez was fresh off his first All-Star campaign and was brought in to help jumpstart the Nationals rebuild.
His first season with the Nats was the best of his career, going 21-8, with a 2.89 ERA, 207 strikeouts, and a 2.82 FIP. With Gonzalez leading the way, the Nationals went from bottom dwellers to World Series contenders, winning their first-ever division title. After the season ended, Gonzalez finished third in NL Cy Young voting.
Gonzalez was key in the Nats winning the NL East four times and he was instrumental in the Nationals owning the best starting rotation for most of the 2010s.
Traded to the Brewers during the 2018 season, he finished his Nationals career 86-65, with a 3.62 ERA, 1,215 strikeouts, and a3.45 FIP.