Before the 2008 season, Kendrick was a victim of an "elaborate practical joke" executed by Brett Myers that had Kendrick convinced he had been traded away to Japan. During the season, Kendrick's performance slipped; he posted a 5.49 ERA in 30 starts. Despite his relative ineffectiveness, the Phillies won the 2008 World Series, and though he was left off the postseason roster, Kendrick received a World Series ring and co-authored a diary from the series. Phillies pitching coach Rich Dubee attributed the decline to hitters discerning that Kendrick threw predominantly a sinker, and almost always in the strike zone, thus fostering predictability for hitters. As such, he spent the majority of the 2009 season in the minor leagues, working on developing his change up, which proved to be an arduous process. Ultimately, after learning a new grip from Justin Lehr, he had a eureka moment during a bullpen session in 2009; he developed the pitch, and made it back to the major leagues "for good" near the conclusion of the season.