Piña reached the major leagues in 1968 with the Cleveland Indians, spending two years with them before moving to the Washington Senators (-), Texas Rangers (), Oakland Athletics (), Chicago Cubs (), California Angels () and Philadelphia Phillies (). His most productive season came in 1972 with the last-place Rangers, when he posted career-numbers in saves (15), strikeouts (60) and games pitched (60). Traded to the Oakland Athletics for Mike Epstein on December 1, 1972, he responded with a 6–3 mark, eight saves and career-highs in ERA (2.76) and innings (88.0), helping them to clinch the ALCS and the World Series Championship. In an eight-season career, Piña posted a 23–23 record with a 3.25 ERA and 38 saves in 314 games. In three post-season games he had a perfect 0.00 ERA in five innings.