I don't know if the knockout game is really on the rise or whether the issue is even important, but I would caution against the general pattern of seeing a blog post which seems to confirm your assumptions and then crowing triumphantly without really engaging the issue.

The blog post you're relying on to describe this as a bogus trend is extremely weak. It offers no new research or evidence and uses faulty logic in at least some parts. I won't write a full takedown but this part seems like a pretty glaring logical error. The blogger points out that an anonymous "Dutchtown woman" says her white son participated in a knockout game and that it isn't a "black thing." The blogger then asks:

How could Torres read this article and yet still come to the conclusion that the assaults are on the rise and that “most” of them involve black assailants and white or asian victims?

Probably because Torres didn't just rely on the opinion of "one Dutchtown woman," looked at the other available articles where racial descriptions were available, and made conclusions based on that.