Pittsburgh optioned the 28-year-old LaFromboise to Triple-A Indianapolis. He was 1-2 with three saves and a 4.75 ERA in 58 relief appearances for the Padres' Triple-A team at El Paso.
San Diego had designated LaFromboise for assignment on Wednesday. He had made his big league debut last year with Seattle, going 0-1 with a 5.91 ERA in 10 games.
Pittsburgh designated infielder Tommy Field for assignment to clear a spot on the 40-man roster. The moves were announced during the Pirates' game Sunday in Milwaukee against the NL Central-leading Brewers.