Twenty-one victories later, he ended that season as the runner-up for the National League Cy Young Award.
Now, in 2011, the 29-year-old Willis is in his ninth season and looks to notch his first victory of the season against the Nationals at Great American Ballpark on Friday.
But even without a win to his credit, the veteran left-hander has pitched well in his time with the Reds this season, recording six quality starts in eight chances.
"I like the way I'm throwing the ball," Willis said after his last start, a six-inning no-decision against the Pirates.
"I like the way I'm competing. I like the way guys are competing for me. We're coming up short on a play here or a pitch there," he said. "I will continue to work hard."
In that start, his second of the season against Pittsburgh, Willis allowed three runs on five hits, struck out five and walked three in an eventual 5-3 defeat.
He was signed by the Reds as a free agent in the offseason, and after making 13 starts with a 2.63 ERA at Triple-A Louisville, he made his team debut on July 10.
Opposing Willis in the opener of a three-game set in Cincinnati is another comeback story in Nationals right-hander Chien-Ming Wang.
After missing an entire season because of an arm injury in 2010, Wang is back in the big leagues and is 2-2 in five starts.
One of those starts came Aug. 16 against the Reds, when Wang pitched 6 1/3 innings at Nationals Park, allowing four runs on seven hits. He didn't strike out anyone, walked a batter and led Washington to a 6-4 win.
The Nationals took two of three from the Reds during that series.
Nationals: Werth injury not serious
Right fielder Jayson Werth was pulled with a sore groin in the ninth inning on Tuesday and was held out of Wednesday's lineup against the D-backs. He returned to the lineup on Thursday and went 0-for-4, while leaving eight men on base.
"It's really mild. I don't think it's going to be a big deal," said Werth, who is hitting .230 with 15 home runs and 48 RBIs this season.
Michael Morse is hitting .350 with 27 doubles, 19 home runs and 62 RBIs in 84 games at first base for the Nats.
Reds: Votto back in lineup
After two days off, first baseman Joey Votto made his return to the Reds' lineup in a big way during the first game of a doubleheader on Wednesday.
Votto hit a two-run home run to left-center field off Javier Vazquez in the third inning of an eventual 6-3 loss. It was Votto's 23rd home run of the season.
A day after starring in front of friends and family in his hometown of Miami, rookie first baseman Yonder Alonso took pregame ground balls at third base on Wednesday.
"There's a chance," Reds manager Dusty Baker said about Alonso getting action at the hot corner. "I'd like to get him in a blowout game -- one way or the other -- first before [he makes a start].
The 24-year-old is hitting .448 with 13 hits in 29 at-bats and two home runs on the season.
Injured Washington catcher Ivan Rodriguez (strained oblique) will begin a rehab assignment on Saturday with Class A Potomac. He is scheduled to catch five innings against the host Frederick Keys.
Left-handed hitters are batting .189 against Willis this season. He has allowed only two extra-base hits to left-handed hitters this season.
The Nationals are 13-11 since July 30, including a 9-6 record in games decided by two runs or fewer.