Keagle was selected in the sixth round, 170th overall, of the 1993 Major League Baseball Draft by the San Diego Padres. He was used almost entirely as a starter in the minors, appearing in only one game in relief before his first call to the majors. His first professional season in the Northwest League with the Spokane Indians was promising (3-3 record, 3.25 ERA), but the first half of his 1994 season was absolutely outstanding. He was 11-1 with a 2.05 ERA in 14 games for the Rancho Cucamonga Quakes and was named to the California League All-Star team. However, that success did not continue after he was promoted to the Double-A Wichita Wranglers, where he was 3-9 with a 6.27 ERA.