Lavelle’s 136 career saves ranked him third among lefthanded relievers on his retirement. He spent 7-1/2 seasons in the minors before being called up by the Giants in mid-1974, but he remained a fixture in San Francisco for the next decade. In 11 seasons with the Giants, his ERA only once was above 3.42. In 1977 he set team records for games (73) and saves (20), and by 1984 he was the Giants’ all-time leader in those categories (breaking Christy Mathewson‘s games mark). Lavelle led NL relievers with 13 wins in 1978. Greg Minton took over as the Giants’ main closer in 1980, and in 1983 he and Lavelle became the NL’s first relief duo to each post at least 20 saves in a season.
Lavelle was traded to Toronto for Jim Gott and two minor leaguers before the 1985 season and led the AL East champions with 69 appearances that season. Chronic elbow problems forced him to sit out the 1986 season. Toronto released him in early 1987, and an attempted comeback with the A’s failed.