Jhoulys Chacin will take the mound on Opening Day for the Colorado Rockies. Manager Walt Weiss made the decision official yesterday. Weiss also announced that veteran lefty Jeff Francis would start the Rockies’ home opener, the fourth game of their season. Jorge de la Rosa and Juan Nicaso are expected to slot between Chacin and Francis in the rotation, with the fifth starters’ job still up in the air.