Annino came to Homewood after spending three seasons as an assistant coach at his alma mater, Amherst College.

At Amherst, Annino helped the Mammoths to a three-year record of 36-9. Amherst posted a 15-4 mark and advanced to the third round of the NCAA Division III Tournament in his first season as an assistant coach (2018) before finishing the 2019 season with an 18-4 record and the program's first appearance in the national championship game. The Mammoths were 3-1 and ranked seventh in the nation when the 2020 season ended abruptly due to the COVID-19 pandemic.