Arizona Cardinals linebacker Kylie Fitts won't be back next season, or any season after the that. The 27-year-old announced on Instagram that he's retiring to protect his health, reports NBC's ProFootball Talk. “Due to too many concussions and the severity of my recent one, it is no longer safe for me to continue to play," he wrote. Fitts, a sixth-round pick of the Bears in 2018, had spent the last three seasons with Arizona. However, he played in only six games last season after suffering a concussion, notes USA Today. His best year came in 2020, when he registered nine tackles over 13 games. (Fitts is only the latest player to call attention to the NFL's concussion problem.)