Myers was the Opening Day starter for the Phillies in 2008. Myers opened the 2008 season weakly; though he pitched deep into games, he did not receive enough run support to cover the number of runs he surrendered. Through the first two months of the season, Myers posted only three wins, as opposed to six losses. His statistics went into a downward spiral as the season progressed, posting a 3–2 record in March and April, a 1–4 record in May, and not winning a single game in June; he went nearly a month without notching a single victory. On July 1, Myers agreed to be optioned down to the minors to address his mechanical issues and focus on pitching. It was reported that he would make at least three starts for the Phillies' Triple-A affiliate, the Lehigh Valley IronPigs, in Allentown, Pennsylvania. He did make one start for the Phillies AA affiliate, the Reading Phillies, and one start for the class-A Clearwater Threshers, to maintain his five-day pitching schedule. He returned to the Phillies and started against the New York Mets on July 23, but did not factor in a decision until his second game back against the Washington Nationals on July 29, where he won his fourth game of the year. Myers pitched strongly through the second half of the season, posting a 7–2 record and a 1.80 ERA heading into the final month of the season. On September 19, he gave up five runs to the first five batters of the game. On October 2, Myers won his first playoff start by pitching seven innings against the Milwaukee Brewers, giving up two earned runs. His key contribution in that game, however, was when he drew a two-out walk against CC Sabathia in the second inning that set the stage for Shane Victorino's clutch grand slam. Myers' next playoff start highlighted his batting skills, as he posted three RBIs and won the game. In the 2008 World Series, he lost his only start in Game 2.