[3] Seaman was traded, along with Tom Grieve, from the Mets to the St. Louis Cardinals for Pete Falcone at the Winter Meetings on December 5, 1978.

Seaman made his MLB debut on September 28, 1979, pitching two innings of scoreless, no-hit relief (although he did surrender two walks) against the New York Mets in the first game of a double-header; the Cardinals lost 6–2.

Seaman remained with the Cardinals for the remainder of the season appearing in 26 games, all in relief, finishing with a 3–2 record, earning four saves.

[2] Following the 1980 season, Seaman was involved in a multi-player trade when the Cardinals sent him along with pitchers John Littlefield, Al Olmsted, and John Urrea, catchers Terry Kennedy and Steve Swisher, and utility infielder Mike Phillips to the San Diego Padres for pitchers Rollie Fingers (who would be traded to the Milwaukee Brewers a few days later) and Bob Shirley, catcher/first baseman Gene Tenace, and minor league catcher Bob Geren.

[3] Seaman finished his professional career pitching for the Vancouver Canadians, the Milwaukee Brewers' AAA affiliate in the Pacific Coast League.