I thought by the title that this thread was about an awesome (knockout) football game!
It IS assault. There are laws that govern deaths caused by assault, but where the assault was not intended to be death. And a judge has the ability to grant minimum or maximum sentences. (like a guy who walked up to a random 70 year old woman and knocked her on the head is not as likely to get leniency than a kid who did the same to another kid, because the 'game' was going around their school)
We should be very careful about deciding what someone else 'deserves' as that is judging, in the form of condemning. Might help to consider that it could be your own teenage son being totatlly STUPID and harming someone with his stupidity, whether he is caught up in a pack of wild dogs (teenage boys in a group can totally be described like that) enabling him to act on the stupidity and cruelty in him, or whether he was cruel and stupid all on his own. You would want your loved one to acknowledge his wrong, repent OF his wrong, make amends... and BE forgiven. No one can acknowledge, repent, and try to make amends, or ask for forgiveness, from the grave.
None of that says that they should be protected from the consequences of their illegal activity. Sometimes that is the only way some people learn; and sometimes the consequence is the only thing that prevents someone from doing stupid harmful things... until such a time as they have learned not to harm simply because harming someone else is wrong.