When the online gaming community first learned that Greg Street was leaving Blizzard Entertainment, many of them worried it was a sign that Ghostcrawler didn't believe in Warlords of Draenor. He did make his departure right after BlizzCon after all. It turns out though, that the spectral crab has instead snapped up an even better opportunity: Lead Game Designer at Riot Games.
The intrepid investigators over at MMO Champion caught the title shift on Street's LinkedIn page -- in what must be the strangest way to find out breaking gaming news in a while. I see this move as a great idea for both Ghostcrawler and Riot: Street gets the opportunity to have more input on game development beyond balancing stats, and Riot gets a top notch systems designer who yearns for more. There's certainly a lot more upward mobility for him at Riot.
Since there is already a lead game designer at Riot, there is a second possibility here: That Street has been brought on to man up additional projects that aren't League of Legends related. Now there's an intriguing prospect.
Within a year, no one will get why my Troll Hunter "Forumstroll" is dragging around a pet crab named "Ghostcrawler"... How dare he ruin my joke (on a character I never play)!
I definitely think Riot is looking to explore more options. I think they should stay somewhere in eSports/competitive though rather than going with 'just another MMO' if they lean towards another game release.