Are playerless match outcomes fixed?

In Dota 2, if the players were to leave the Radiant and Dire creeps to play the game out without doing anything in game, is the fate of the match set (favored towards Dire/Radiant), or is it entirely random?

I'm just curious to see if anyone knows if a match that is played out with players on both sides not participating and letting the creeps duke it out would result in one side winning all the time or just Radiant winning some and Dire winning some?