In his freshman season, Massinburg was not expected to contribute much, but ended up playing a key role off the bench averaging 11.3 points and 4.1 rebounds per game, earning a spot on the
Mid-American Conference (MAC) All-Freshman Team. As a sophomore, Massinburg's progress was slowed by missing the first eight games of the season due to a bout with
mononucleosis, but he improved his scoring to 14.5 points per game as he moved into the starting lineup. As a junior, Massinburg was named first-team All-MAC as the Bulls enjoyed regular-season and Tournament conference championships, earning a trip to the
2018 NCAA tournament. Massinburg scored 19 points in the Bulls' upset over 4-seed
Arizona in the NCAA Tournament's first round, thought to be the biggest win in program history at the time. As a senior, Buffalo was the overwhelming preseason choice to win the MAC and Massinburg was named preseason first-team All-MAC East. The Bulls experienced great team success, as the team achieved a top 25 ranking in the November 12, 2018
AP Poll, signifying a first for the school. The Bulls would go on to maintain a spot in the top 25 for the remainder of the year. Massinburg led the team in scoring, moving into the school's top five all-time scoring list on January 29, 2019. He received national individual recognition as he was named to three watch lists for several national Player of the Year awards. Massinburg closed the
2018–19 regular season averaging 18.5 points per game and winning MAC Player of the Year honors and repeating on the all-conference first team.
The Buffalo News named Massinburg the best player of the decade from Buffalo,
Canisius,
Niagara, or
St. Bonaventure. He was also named to the
Lou Henson Award All-Decade Team. ==Professional career==