A triple jump specialist, Plummer was an honorable mention all-American as a junior after placing 21st at the NCAA championship. The 2016 Outdoor Heps champion in the event, he was the runner-up as a senior the following year and took third in 2015 as a sophomore and sixth as a freshman. The two-time NCAA East Prelim qualifier, he won the IC4A/ECAC Infoor title and graduated fifth indoors and third outdoors in school history in the event with a best of 52-6 3/4 leap in his final season.