A while back we looked at Radiant vs Dire win rates in 6.74 and 6.77 and found that Radiant had a slight overall advantage that was most pronounced in short games and actually became a disadvantage during long games. While we don’t have absolute proof, it’s generally accepted that the late game Dire advantage is driven largely by the positioning advantage Dire has for Roshan. But when it comes to the other side of the dynamic, Radiant’s advantage during short games, all we have are competing theories with no clear evidence. Recently in League of Legends, a stat site released some data on the balance between their sides in various modes, and the implications could help explain what’s going on.
For those unfamiliar, the LoL Blue team corresponds to Radiant positionally and Purple corresponds to Dire. The default LoL map has some asymmetry, but nothing to the extent found in the Dota map. What the stats show is that on the standard League map, the Blue side has a significant advantage in all modes (Unranked: 56.3%, Ranked: 55.2%, Ranked Teams: 53.5%).
Where things get interesting is that the same advantage exists in ARAM (55.4%) which is a perfectly symmetrical map. This is the strongest evidence I’ve seen that the Radiant advantage is related to the viewing perspective/camera angle. The LoL map with the smallest side advantage is Dominion (51.8%), which also happens to be the only map tested without a diagonal tilt, as the map is East/West symmetrical.
It’s still not proof, but I think there’s decent evidence here in support of the camera angle theories. Dire’s inherent Roshan advantage could actually be rather appropriate. Roshan’s positioning would likely have the greatest net effect in low level games as low level games have the longest average duration. These also might be the players least capable of dealing with the camera disadvantage, and therefore most in need of a larger counterbalance. It’s fairly speculative, but it would be a pretty unique feature if both the Radiant and Dire advantages separately scaled at a similar rate with the overall skill of the players in the game.
DotaMetrics 
Just wanted to say that what you are doing with Dotametrics is great! Keep up the good work, much appreciated.
If I had to guess, I wouldn’t think that lategame dire side advantage would be as present (or even present at all) in lower skill games. Roshan advantage is reliant on teams actually contesting it, when many players won’t even attempt it and the odds that a team has warded it later in the game or correctly reads a Rosh attempt is fairly low.
I’ve wondered about the camera thing before, but I think in order to actually question why that might be the case someone would to be really well versed in some particular field of study, like physiology, if it’s a case of the mechanical difficulty of playing on dire vs radiant, or psychology, if it’s a perceptive thing.
If it really amounts to such huge % bias that’s a bit shocking, though it’s reassuring that in most competitive arenas, both teams will play on either side of the map. For those tournaments that split up reverse fixtures across a few weeks, they should probably make sure that the teams play on both sides of the map.
And in response to harmonica: I don’t think it even has to be a psychology thing. It simply means that radiant has a slightly larger view of their enemy, which is bound to give an advantage.
Ha, I knew it!
http://blog.dotateam.me/a-potential-explanation-for-the-increased-win-rate-of-the-radiant/
I always preferred playing Radiant, ever since they were called the Sentinels.
Now I know it was just my inner tier-whore min-maxing.
I wonder if it would help much if they implemented that when you’re on Dire, Dire’s base is positioned on the bottom left corner of the map. So you’d essentially see just a rotated version of the map.
Ye Dagda, I thought about that too, I think it is possible as seen in some other games (in different manners, however), but if someone could make it work in a MOBA hats off to them. I wouldn’t know how to do it if my life depended on it. Way harder for a multiplayer; live game
The best theory I’ve seen is that the advantage comes from the mechanics of edge scrolling. Alternating between scrolling upwards a little and clicking targets is easier than alternating between scrolling downwards and clicking targets because there’s less UI in the way.
During the laning phase, Radiant side clicks on more targets above them than Dire does.