Venable scored three times while Jedd Gyorko smashed a three-run homer and Nick Hundley connected for a two-run shot as San Diego snapped a three-game skid.
Edinson Volquez (9-10) went five innings en route to the decision, yielding two runs on seven hits and two walks. The right-hander struck out five.
Mets reliever David Aardsma (2-2) absorbed loss after starter Jenrry Mejia left after three innings with elbow discomfort.
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