My cousins like to play and watch League, but I never did. That said, we did an impromptu road trip to LA awhile back to watch some professional games live. As someone who never played and only watched a handful of games, it was really a ton of fun and not that difficult to follow. Though they're far from perfect, the announcers do a pretty good job of explaining the action. From a layperson point of view, I really only needed to know whatever the super attacks were for the characters and could figure that out pretty quickly with the help of the announcers.

Really, I think what helps League over StarCraft is that it's pretty clear who's winning and who's losing since there's a relatively easy to follow flow across the map. When one team loses their towers, which are clearly denoted, they're probably behind. Further, gold and experience also give a pretty good indication of who's winning and losing. With StarCraft, which I've also never played, but have watched a handful of games, I find it difficult to follow on a macro scale. Certainly, it's easy to see when one battle is won or lost, but then suddenly one player will concede and I'm left wondering why. I think that rapid nature of forfeiting and loss of the game hurts its spectator appeal.