Marquis, who will start Friday in Philadelphia, has pitched well in his past five starts, although he has just a 2-3 record to show for it. An example of his tough luck came Saturday, when he took the loss against the Marlins despite striking out eight and giving up just two runs over six innings.
"He's been real good," Nationals manager Jim Riggleman said. "He's doing what we thought he'd do when we signed him. He's giving us innings. He's pitching with confidence [now] that his arm feels good."
Marquis, 32, signed a two-year, $15 million contract with the Nationals as a free agent after winning 15 games last season with the Rockies. But his elbow started aching midway through Spring Training, and he had to go on the disabled list after three regular-season starts in which he was 0-3 with a 20.52 ERA.
The right-hander is 2-5 with a 3.77 ERA in seven starts since coming off the DL. He has won two of his past three decisions and has allowed only eight runs over 30 innings in his past five outings.
"So far, so good," Marquis said. "My elbow is feeling better and better."
Marquis is 0-3 against the Phillies this season, but two of the losses were before he went on DL. He allowed four hits and a run over five innings on Aug. 20 in his most recent start against them.
Marquis will pitch on Friday even though he is Jewish and it will be Kol Nidre, the start of Yom Kippur. He previously pitched on Yom Kippur, the Jewish Day of Atonement, while with the Braves and Cubs.
"I made the decision when I came up to the Majors that I wouldn't miss any starts," Marquis said. "Your team expects you to do your job. That's the approach I take."