the games before shorter is probably directly related to minions getting to lane slightly sooner, the passive gold you get is increased as well.
Some of the earlier items have changed their stats a little bit, which i think help out the early game slightly.
these add up to power spikes being met sooner, which translates to using those spikes sooner and more effectively.
Which of course, means you appear to have a stronger lead.
However i feel that if you can push past their power spike with lets say, Shyvana.
if you can manage to get through their moment if "op", Shyvana's late game will surely turn the game around.
i mean, its a power spike, Its meant to be hard, its meant to overwelm the enemy, you're meant to win while in your power spike.
i feel like during the pre-season changes, these power spikes we all knew of are being used a lot more, rather we know we are, or not.
that's why some games are shorter than others.
Personally, i'm okay with this, because we have one counter play against it.
Don't Lose. ~ and outscale.
you don't need to win....you just need to not lose. :)