The following season, 1970, Behney made his debut in the Major Leagues with the first incarnation of the Reds' "Big Red Machine" team that dominated the National League West Division race, winning by 14 games, then swept the Pittsburgh Pirates in the 1970 National League Championship Series. In his debut on August 14 at Riverfront Stadium against the Philadelphia Phillies, he relieved starter Wayne Simpson in the fourth inning of a scoreless contest, but gave up five hits and five runs (three of them earned), and was pinned with the defeat in a 5–4 Philadelphia win.