The next year, due to a necessity at the closer role, he was converted into the Rockies closer for the 2004 season. Chacón put up one of the most bizarre stat lines in baseball history for a closer. Chacón was ninth in the National League with 35 saves but was also tied with a league leading nine blown saves. His record was 1–9 and his ERA 7.11. His home/road splits were even odder, as he was 1-5 at home with a 6.81 ERA and 20 saves. He allowed more hits than innings pitched, and while on the road his ERA was even worse, standing at 7.56 and notching only 15 saves. In 2005, Chacón was 1-7 with a career low 4.09 through 13 games before being traded mid season to the Yankees, ending his five-year tenure with the Rockies. A few months prior to the trade, Chacon told a sports reporter that nobody wanted to pitch at high altitude Coors Field because the ball would not curve in the light air. After Chacon went to the Yankees, Rockies manager Hurdle said that a player unhappy with the Rockies would leave quickly. He finished 24-45 in 150 games with 35 saves for the Rockies.