Staying in Stockton out of high school, Bennetts spent his first two collegiate seasons pitching for the Mustangs at Delta Junior College. In 2013, Bennetts went 2-2 with one save in 34 innings pitched. He picked up 20 strikeouts while sporting a 3.71 ERA. In 2014, Bennetts put together a 9-3 campaign as a starter with a 2.71 ERA in 89.2 innings pitched. For his play he earned Second Team All-Big 8 honors.

The standout of the Lincoln High School pitching staff, Bennetts earned team MVP honors for his play while taking home First-Team All-San Joaquin Athletic Association honors. As a senior, Bennetts appeared in a team-high 14 contests with 10 starts. He threw six complete games while sporting a 2.79 ERA and a 4-4 record. In relief, Bennetts picked up a pair of saves.

In 2015, Sean had a three-game winning streak against BYU, Gonzaga (in Spokane, WA), and Seattle University.  As a junior, he is expected to be a mature presence on the Goldpanners staff.