 He reached the majors with the San Francisco Giants late in the season, spending four years with them before being traded to the Chicago Cubs, along with Bobby Murcer, for Bill Madlock before the 1977 season.1977 ended up being his most productive season for the Cubs, when he posted career-highs in games played (156), batting average (.299), home runs (10), RBI (68), hits (162), and on-base percentage (.390).On April 17, 1977, Ontiveros broke up a no-hit bid by the New York Mets' Tom Seaver with a bloop single in the fifth inning.