Burdi (elbow) underwent Tommy John surgery in October and was designated for assignment by the Pirates on Sunday, Adam Berry of MLB.com reports.
The 27-year-old received a platelet-rich plasma injection in August to avoid surgery at the time, but the treatment apparently didn't have the intended impact. Burdi has now been removed from Pittsburgh's 40-man roster as he'll miss the entirety of the 2021 while recovering from his second Tommy John surgery.