He started 11 games for them, going 4–6 with a 5.00 ERA. Milwaukee Brewers Davis signed with the Milwaukee Brewers after becoming a free agent in mid July. He made 5 starts in AAA before being called up on August 11, 2003. On September 19, he allowed a home run to Hall of Fame pitcher Randy Johnson, the only home run of his career. Davis was an anchor for the Brewers in 2004. He had career bests in all pitching categories, notching 12 wins while allowing a career low 14 home runs. Davis continued with the Brewers in 2005, going 11–11 with a 3.84 ERA. On Mother's Day, May 14, 2006, Davis was one of more than 50 batters who brandished a pink bat to benefit the Breast Cancer Foundation. Davis made a brief appearance in 2005 as a potential home buyer on the A&E television program Flip This House episode "It's a Rat Race". He finished the 2006 season 11–11 with a 4.91 ERA and 102 walks. Arizona Diamondbacks On November 25, 2006, Davis was traded to the Arizona Diamondbacks along with pitcher Dana Eveland and outfielder Dave Krynzel, for catcher Johnny Estrada, and pitchers Greg Aquino and Claudio Vargas. The Diamondbacks and Doug Davis agreed to a three-year, $22 million deal. In his first season for the Diamondbacks, Davis went 13–12 with a 4.25 ERA and 144 strikeouts in 192 innings. On July 29, 2008, Davis took a perfect game into the bottom of the 7th inning at Petco Park. Davis' 2008 season was cut short due to injury, making 26 starts, and finishing with a record of 6–8. On August 12, 2009, Davis' former team, the Milwaukee Brewers, put a waiver claim on him, but he was not traded. Davis ended the season with a 9–14 record, with a 4.12 ERA and 1.51 WHIP. He tied for the major league lead in errors by a pitcher with 5, and also led the league in walks with 103. Second Stint with Brewers On January 22, 2010, Davis signed a one-year contract with the Milwaukee Brewers for $4.25 million in 2010, with a $6.5 million mutual option for 2011 with a $1 million buyout. Davis endured a rough season in 2010, making only 8 starts and going 1–4 with a 7.51 ERA. He spent most of the season on the disabled list. His option was declined after the season.