Francis (1-1) saw his career spiral downward after shoulder surgery, but is attempting to make a comeback with the team that originally drafted him. He spent his first six years in the majors with Colorado before pitching for Kansas City last year.
He gave up three hits against the Padres and walked one while throwing 82 pitches.
Colorado secured the victory by scoring four times in both the sixth and eighth innings. Two San Diego errors helped the Rockies in the sixth and they got two-run homers from Michael Cuddyer and Wilin Rosario in the eighth.
Jason Marquis (1-4) allowed six runs on six hits in six innings while suffering the loss, the seventh for San Diego in 11 games.