It's an anime show that put Cartoon Network's Adult Swim block on the map. It's one of the best written shows (animated or live action) most people have ever seen.
The song "Blue" was featured in the last part of the last episode, which (trying not to be spoiler-riffic here) featured someone going to a higher place.
It's the perfect song for someone leaving for the WWE, and I'd wager there's a high enough crossover between ROH fans and Adult Swim fans for it to get over. Especially if the final match was a bloody brawl, and the guy leaving just limped to the house mic to say his farewell speech.
"Bang."