The Rockies seem to be so impressed with third-base prospect Nolan Arenado that they're in the process of clearing the way for him to make a serious run for the starting position next year.Colorado took another step in that direction Sunday, trading incumbent Ty Wigginton to Philadelphia for a player to be named later or cash. Arenado, 20, hit 20 homers, drove in 122 runs and batted .298 at Class A Modesto in 2011, and he just came off a stellar Arizona Fall League session in which he earned MVP honors. The Rockies responded to that potential by moving Wigginton, a proven Major League hitter with some right-handed pop who can play multiple positions. Wigginton has hit more than 20 homers in a single season four times in his 10-year career, and he's a career .265 (1,087-for-4,107) hitter with 232 doubles, 14 triples, 158 home runs and 548 RBIs in 1,190 games. He has at least 15 home runs in seven of his last eight seasons. Contenders for the Rockies' starting third-base job in 2011 also include Ian Stewart and possibly Brandon Wood, who was signed to a Minor League deal earlier in the week.