Atlanta expanded its lead in the National League East to 5 1/2 games, taking the lead for good with a three-run sixth and then piling on five more runs over the next two frames.
Pena had an RBI single in both the second and sixth innings and drove in two more runs with a base hit in the seventh. His single in the sixth brought home Evan Gattis with the go-ahead run.
Mike Minor (7-2) went seven innings to get the victory, although he allowed three runs in the sixth that briefly tied the contest. Minor struck out five without a walk.
R.A. Dickey (4-7) was roughed up for six runs on 11 hits in six innings to take the loss.