There's more information here that you might not have heard.
-- The victim, the victim's mother, as well as many other kids at their Jr. High describe a long-term pattern of abuse:
"Meyer-Crothers, also 18 and who now lives in Detroit, said Miller had taunted him for years, constantly calling him "brownie" and the "N-word," while repeatedly hitting him while growing up in the Toledo suburb. Other students at their junior high confirmed to police that Miller repeatedly used the "N-word" in referring to Meyer-Crothers."
-- "The incident happened during warmups of the game and about 40 kids can be seen watching the attack, said Ms. Meyer-Crothers. She said one of the girls who reported it to the school’s principal also said she had seen Isaiah bullied so many times that she just got sick of it."
-- The victim and the victim's mother claim that Miller had been assaulting the victim for many years, going back to when they were ~8 years old. (A lot of this was reported in the Toledo Blade back then and I've gone through all of my free articles right now, perhaps you can find the quotes). The victim's mother says the "incident" is just the thing that got Miller caught, that there was years of stuff that he's never owned up to.
Contrast all of that information with the statement from Miller that talks about "an incident that happened four years ago, when I was in 8th grade". It sure looks like Miller hasn't yet fully owned up to his past.