IIRC, the story was timed for 1984, after the time boxing was banned between humans.
Apparently Rod Serling was a “pro-class” boxer while a paratrooper during WW2. He also wrote another TZ tv episode about boxing titled “One Tall Wish”...starring a young Ivan Dixon (of later Hogans Heroes fame and Ivan was involved in making movies also). He was one of the rare black actor TV show protagonists for the time.
Serling also wrote “Requiem for a Heavyweight”
FYI
Here’s a sort video about Lee Marvin, wounded WWII Marine veteran, Saipan and Iwo Jima............
https://www.youtube.com/watch?v=KkNmdgx7jvc