With Adreian Payne and Gary Harris leaving MSU for the NBA Draft, Keith Appling leaving due to graduation (eventually to the NBA), the dismissal of Kenny Kaminski, and the transfer of Russell Byrd, Valentine saw an increase in leadership and an expanded role on the team as a junior. Before the season started, he was awarded one of the three captain spots. Perhaps one of Valentine's most memorable moments came on Valentine's Day 2015, he hit the game winning shot in a matchup versus Ohio State and finished with 17 points. His junior season saw him earn Orlando Classic All-Tournament Team (averaging 19.3 points and 5.0 rebounds in three games), Third Team All-Big Ten, USBWA All-District V, and NCAA East Regional All-Tournament Team honors.