To check whether you are lagging or not, there should be a ping test when you log into PvP.net. If you fail the test and have 200+ ping, then you should not be allowed to queue for games until you retest for a ping higher than 190. The test should be robust to account for some idiots with wildly fluctuating pings. The same test could be applied after champion select, automatically kicking anyone who might fail.
The reason for this? I am getting teammates in ranked with 250+ ping. Needless to say, they feed then say "sorry, lagging". This ruins the game for everyone. Have this built in safety feature and the lagging problem will be almost completely solved.
I'm amazed there isn't such a feature already.