Hoffa, who also was a star at Georgia and is a former Olympian, won it with a throw of 71 feet and a half inch.
Canada's Dylan Armstrong finished second at 70-101.
Defending champion Allyson Felix finished third in the 400 meters and world champion Caster Semenya placed second in the 800 in her American debut.
Amantle Montsho, of Botswana, won the 400 in 50.59 seconds, while Felix crossed in 51.41 to trail fellow American Debbie Dunn by 0.04. Felix is a three-time world champion and a two-time Olympic silver medalist in the 200.
Semenya timed 1 minute, 58.88 seconds to finish 0.59 behind Kenia Sinclair, of Jamaica. The South African won the event at the 2009 world championships but was unable to complete for much of last year because of controversial gender testing.
Jamaican Steve Mullings won the 100 in a meet record 9.80.
American Carmelita Jeter won the 100 in a meet record 10.70, a world best this season.
Walter Dix defended his Pre 200 title in 20.19 seconds.
American David Oliver, the bronze medalist in the 110 hurdles at the 2008 Olympics, won the event in 12.94, besting Liu Xiang of China by 0.06.
Angelo Taylor, two-time Olympic gold medalist, won the 400 meters in 45.16.
American Bernard Lagat won the rarely contested 2-mile run in 8:13.62, while Ryan Gregson of Australia ran the Pre'sInternational Mile in 3:53.86. Haron Keitany, of Kenya, won the elite Bowerman Mile in 3:49.09.
Abubaker Kaki Khamis won the men's 800 in a meet record 1:43.68.
Kenya's Ezekiel Kemboi won the men's steeplechase in 8:08.34.
Ukranian triple jumper Olha Saladukha won her event with a leap of 49 feet, 13/4 inches.
American Lasinda Demus defended her Pre title in the women's 400 hurdles in 53.31.
Nadeshda Ostapchuk of Belarus won the women's shot put with a throw of 67-63/4, while Germany's Robert Harting won the discus with a throw of 224-5. Countryman Raul Spank won the high jump with a leap of 7-71/2 inches.