The 24-year-old joined Leverkusen from Belgian side Royale Union SG two years ago and quickly made an impression.
Initially signed as back-up to Czech striker Patrik Schick, Boniface seized his chance when Schick was sidelined through injury. Under Xabi Alonso, he delivered consistently, scoring freely and maintaining his starting role even after Schick's return.
Boniface has since amassed 32 goals and 13 assists in 61 appearances for the German champions. However, his momentum has often been disrupted by injury.
A lengthy absence midway through his first campaign saw him lose his starting spot, and although he regained it last season, further setbacks again limited his influence.
With Ten Hag taking charge in the summer of 2025, Boniface has found opportunities harder to come by. He featured sparingly in pre-season and was notably overlooked in the recent DFB Pokal tie against Grossaspach.
Despite being named among the substitutes, Ten Hag turned to new signing Christian Michel Kofane when Schick was withdrawn. The Cameroonian striker responded with a goal and an assist in a convincing 4-0 win.
According to German outlet Bild, the Dutch coach now considers Boniface his third-choice striker, behind both Schick and Kofane.