I have a quad surround sound setup and when playing League of Legends, sounds that originate at the bottom of my display playback on my rear speakers and sounds that originate at the top of my display playback on my front speakers. This behavior doesn't make any logical sense to me, but I'm pretty sure it is intended.
As a player of League of Legends, you are looking almost straight down onto the action. I am a surround sound lover, but this scenario just doesn't call for surround sound. In fact, artificially creating surround sound in this way I find distracting and annoying to the point where I almost want to set my sound settings to stereo if it weren't such a hassle to switch back and forth between that and quad.
I'm a fan of "sound at camera". From what I remember, the surround sound in Warcraft III used this philosophy. I think the rear audio surround sound would be much better in League of Legends if it had that kind of approach. The rear could be used for lightning, for example, with cool reflective effects from the front. Or if an arena was indoors, there could be awesome reverb coming from the roof.
I would love to see the game's surround sound revisited or a "sound at camera" option kinda-sorta like World of Warcraft's "sound at character" option implemented.