Holliday's first career multi-home run game came against the Cincinnati Reds on May 18. Both home runs came as part of back-to-back home runs events with Burnitz, making them the first teammates in franchise history to hit back-to-back home runs twice in the same game, and the first teammate duo to do so since Mike Cameron and Bret Boone of the Seattle Mariners in 2002. His first MLB grand slam came against the Tampa Bay Devil Rays on June 12, immediately tying a game in which the Rockies had faced a 5–1 deficit. For the month of June, he hit .357. The Rockies traded Walker to the Cardinals in August, clearing more outfield playing opportunities for Holliday. A sprained elbow while diving for a ball against the San Diego Padres on September 12 ended his season. His final batting line included a .290 batting average in 121 games, with 31 doubles, 14 home runs, 57 RBI, 65 runs scored, 48 extra-base hits, .349 on-base percentage, .488 slugging percentage, and 195 total bases. He finished in the top five among NL rookies in each of those categories. After the season, Holliday was named to both "Baseball America"'s All-Rookie Team and Topps' Major League Rookie All-Star Team, and finished fifth in the Rookie of the Year balloting.