Playing in 160 games, he scored 97 runs, to go with 191 hits (7th in the NL) and 34 doubles. His 40th home run came in the last game of the season. He finished the year hitting .304 with 113 RBIs. At third base, he was NL leader in double plays turned (43) and assists (389). For the 1997 season he would have exactly the same totals of home runs, RBIs and batting average (40/113/.304) than the prior year, as well as three multi-homer games. He earned his second Silver Slugger Award in three years. Defensively, for second year in a row, he led the league in both assists (323) and double plays for a third baseman (41). Castilla's most productive season was 1998. On opening day he hit the first ever home run at Bank One Ballpark of Arizona Diamondbacks. That year he earned his second All-Star nod and his first Home Run Derby selection, in front of his home crowd in Colorado. Playing in all 162 games, he finished the season with 46 home runs (4th in the league), 144 RBIs (3rd), 206 hits (3rd), 380 total bases (3rd), 108 runs scored and a .319 batting average (10th in the league), all career-highs and good enough numbers to finish 11th in the NL MVP ballot. On April 4, 1999, Castilla was a part of history as the Rockies played their Opening Day contest in his native Mexico at Estadio de Béisbol Monterrey in Monterrey. The game marked the first time MLB commenced the regular season outside of the United States or Canada. The Rockies' opponent were the defending National League champion San Diego Padres. Castilla delighted the crowd with four hits including a double, as Colorado won 8–2. During the Monterrey series in Mexico, Castilla switched briefly to number 14 on his jersey, in honor of former Rockies first baseman Andrés Galarraga (then with the Atlanta Braves), who was diagnosed with cancer and missed the entire ‘99 season. On June 6, 1999, Castilla produced his first career three-home run game against the Milwaukee Brewers. His offensive numbers slightly declined, hitting for a .275 batting average (first time in 5 years he failed to eclipse the .300 mark) He finished the season with 33 home runs, but for the 4th year in a row he had 100+ RBIs (102). He had the 3rd highest number of errors at third