How can an item that everybody gets every game doesn't have a 50% win rate?

I was browsing the statistics on LoLKing and found something odd.

http://www.lolking.net/charts?region=all&type=item-popularity&range=monthly&map=ha&queue=normal

On Howling Abyss (ARAM map), the Cookie, given to every player at the beginning of the game, is not exactly 50% win/loss. (We are talking about 50.15%)

How could this happen? How can an item that everybody (event the afks) gets every game doesn't have a 50% win rate?

Solution 1:

The champion Rengar does not receive the Poro Snax, instead he has his bonetooth necklace trinket. This would explain the small gap in wins-loses.