Complex sentence: Moving from left field to right field, he dramatically increased his offensive production by hitting.297 with 21 HR and 67 RBI, resulting in him became a starter for the rest of his career in Houston.
Split into simpler sentences: Moving from left field to right field, he hit.297, with 21 HR and 67 RBI. This firmly established him in the Astros lineup, and he became a starter for the rest of his career in Houston.