The Nationals have won two straight after losing five in a row. They broke their losing streak Wednesday by scoring twice in the ninth inning to defeat the Diamondbacks 5-4.
Detwiler (3-1) gave up all three Arizona hits and was relieved by Ryan Mattheus with a runner on second and one away in the seventh. Mattheus retired the only two men he faced to preserve the 2-1 lead, and Tyler Clippard and Henry Rodriguez worked a perfect inning each, with Rodriguez earning his sixth save in seven chances.
Washington produced the go-ahead run in the bottom of the sixth on doubles from Ian Desmond and Bryce Harper.
Ian Kennedy (3-1) suffered the setback, allowing both Washington runs on four hits in seven innings.