Kristaps Porzingis looked like he was hitting his stride at the end of the regular season. But by the end of the playoffs, the big man struggled to consistently stay on the court as his mysterious illness sapped his strength.

Brad Stevens shed some light on the mysterious illness that plagued Kristaps Porzingis during the Celtics' playoff loss to the New York Knicks.

Celtics general manager Brad Stevens announced the latest on Porzingis during his end-of-season presser on Monday, via The Athletic's Jay King. "Brad Stevens said the way Kristaps Porzingis’ illness was described to him was as 'post-viral syndrome,'" he reported. "Said playoff basketball was not conducive to helping him feel better."