Complex sentence: He spent four seasons as the Sox's minor league infield instructor before being promoted to the major league club in the same capacity while also serving as their first base coach for two seasons before returning to his previous position as roving infield instructor in 2005.
Split into simpler sentences: He spent four seasons as the Sox's minor league infield instructor before being promoted to the major league club in the same capacity while also serving as their first base coach for two seasons. Santana returned to his previous position as roving infield instructor in 2005.