I am actually astounded it took this long for Riot to make this change, particularly when you consider the kind of data it had available. Granted, these stats were probably taken after the launch of Season One, but it wasn’t exactly uncommon to see players below level 30 matched with those above prior to the Season One launch either.
As Pendragon stated in a post last night, the change was made because players below level 30 tend to leave 4.2 percent of games, versus the 1.1 percent of games from level 30 players. The really interesting stat, though, is that sub-30 players have a staggering 35.2 percent win rate, while those over 30 are seeing an average 52 percent win rate.
Again, I’m shocked it took this long, and the data serves as a pretty embarrassing statement toward Riot’s foresight on this. You should start to see the change today.