[5] As a sophomore in 2018, he started 52 of 53 games and batted .328 with ten home runs and 32 RBIs,[6] earning First-Team All-CAA honors.

[7] After the season, he played for the Upper Valley Nighthawks of the New England Collegiate Baseball League[8][9] where he earned All-Star honors.

[10] In 2018, Jeffers' junior season at UNCW, he slashed .315/.460/.635 with 16 home runs and 59 RBIs over 62 starts,[11] earning a First-Team All-CAA selection for the second consecutive year.

[3][22] In 2019, he began the year with the Fort Myers Miracle, with whom he was named a Florida State League All-Star, before being promoted to the Pensacola Blue Wahoos in July, with whom he finished the season.

[27] He made his major league debut that same day against the Milwaukee Brewers, recording two hits including one RBI over three at-bats in a 7–1 win.