User blog comment:Ysana/Uohhhhhhhhhhhh Influence Points!/@comment-4834593-20120630051212

Well, they started with only 450, 1350 and 3150 IP champions, so there were at the start no 6300.

And why somewhat higher numbers? I think it's because, this way, it's easier to give points for the time the game lasted. Otherwise, long and short games would give an equal amount of IP, so there would be no reward for playing longer.