Saturday, May 31, 2014

Blue Side Advantage Part 2

I feel that there needs to be a continuation on the topic of blue side advantage due to two things readers brought up:

1. Whether or not the blue side advantage is affected by players' skills; e.g. perhaps Diamond/Challenger players are less likely to be affected by this advantage, and by extension, in the competitive scene the blue side advantage is minimal.
2. Whether or not this effect depends on the champion you play. I hope the previous post convinces you that the blue side advantage is mostly due to camera angle (since One For All Mirror Mode removes all other factors); so there is a possibility that champions with long range skillshots are affected by blue side advantage more than champions with short range.

My answers to these two questions are:

1. Blue side advantage is affecting high level players (Diamond/Challenger) just as much as low level players (Bronze). 
2. There are some differences between champions and how they are affected by the blue side advantage. Short range champions are slightly less likely to be affected by the blue side advantage. Rumble, in particular, is affected by this so much that he wins 57% of the time on blue side and only 41% on purple side.


The data and the analysis:

1. Blue side advantage vs players skill.

For this, I pulled roughly 1.8 million games played in patch 4.6 and 4.7, all of which are ranked. The results are as below:

   Blue Side Win % Purple Side Win % Difference Total Win % Games Recorded
Challenger 59.75% 49.35% 10.41% 54.59% 17299
Diamond 56.53% 46.92% 9.61% 51.73% 1035553
Platinum 55.88% 46.32% 9.55% 51.11% 2756535
Gold 55.94% 45.98% 9.96% 50.96% 5656094
Silver 55.11% 44.44% 10.67% 49.77% 7744235
Bronze 53.10% 41.27% 11.83% 47.18% 2675229
First of all, if we only look at the chance of winning on blue side, it seems that at nearly 60%, Challenger players are even more heavily affected by the blue side advantage. However, a closer examination shows that Challenger players are so good that they win 55% of the time overall, so their blue side win rate is inflated. To counteract this, I take the difference of the blue side win rate and the purple win rate. This gives us a roughly 10% difference in win rate for blue side vs. purple side for all league players. We will be using this number to examine the size of the blue side advantage.

Also, although this chart does not show this, Challenger players have equal chance to play on blue side or on purple side. 

Therefore, we see that blue side advantage decreases very slightly as the players' skill increases. However, blue side still wins roughly 10% more often than the purple side - which is roughly the same as saying blue wins 55% of the time.

(Comment: sorry if you are a statistics buff. I chose to not use relative risk or odds ratio because I feel risk difference is far easier to interpret)

2. Blue side advantage vs champion

This time, instead of having one row per league tier, I plotted the table to have one row per champion. I only chose champions that had at least 50,000 games to avoid looking at the potentially misleading numbers that may be produced by champions that are rarely played (yes you, Urgot).

Similar to our analysis before, we are going to look at the difference in win rate between blue and purple side - because some champions are so strong that they win ~55% of the time overall, similar to Challenger players in ranked. I sorted this table so the champions with the greatest blue side advantage are on top, and the ones with least blue side advantage are on the botttom.

Champion Blue Side Win % Purple Side Win % Difference Total Win % Games Recorded
Rumble 57.34% 41.71% 15.63% 49.54% 53239
Jayce 54.91% 43.35% 11.56% 49.14% 90014
Shaco 56.77% 45.23% 11.54% 50.92% 93684
Olaf 49.93% 38.43% 11.50% 44.14% 59337
Teemo 57.10% 45.72% 11.38% 51.34% 136910
Veigar 52.42% 41.09% 11.33% 46.71% 57354
Velkoz 56.24% 44.97% 11.27% 50.62% 79882
Brand 57.35% 46.10% 11.25% 51.76% 76920
Lux 56.18% 44.94% 11.24% 50.59% 224541
Malzahar 58.26% 47.06% 11.20% 52.60% 86484
Nidalee 55.58% 44.42% 11.16% 50.09% 392071
Draven 56.93% 45.78% 11.15% 51.46% 186644
Ahri 54.16% 43.02% 11.14% 48.61% 119034
Chogath 52.00% 40.88% 11.12% 46.42% 68512
Varus 55.42% 44.39% 11.03% 49.92% 140731
Lissandra 52.74% 41.75% 10.99% 47.18% 54384
Ziggs 58.70% 47.76% 10.94% 53.26% 256552
Volibear 55.23% 44.30% 10.93% 49.72% 119082
Amumu 58.87% 47.95% 10.93% 53.32% 141434
Syndra 54.74% 43.84% 10.91% 49.30% 150155
Elise 50.20% 39.30% 10.90% 44.68% 103848
Singed 56.71% 45.82% 10.89% 51.24% 59682
Talon 57.47% 46.59% 10.88% 51.96% 74872
Morgana 57.71% 46.84% 10.87% 52.23% 648008
Sivir 54.84% 43.98% 10.86% 49.26% 159978
Heimerdinger 58.39% 47.57% 10.82% 52.95% 70838
Hecarim 52.35% 41.54% 10.81% 46.91% 57400
Jinx 57.07% 46.29% 10.78% 51.73% 440826
Blitzcrank 56.18% 45.42% 10.76% 50.85% 248811
Aatrox 55.13% 44.41% 10.72% 49.69% 74615
Karma 53.86% 43.14% 10.71% 48.51% 239518
Caitlyn 55.53% 44.84% 10.69% 50.17% 709054
LeeSin 51.97% 41.29% 10.68% 46.62% 490862
Trundle 53.94% 43.26% 10.68% 48.55% 118351
DrMundo 51.78% 41.16% 10.62% 46.47% 87591
Rengar 54.32% 43.73% 10.60% 49.03% 97593
Nasus 55.41% 44.81% 10.59% 50.10% 233418
Shen 50.55% 39.96% 10.59% 45.29% 87704
TwistedFate 53.22% 42.64% 10.58% 47.93% 125955
XinZhao 57.88% 47.35% 10.53% 52.63% 318665
MissFortune 58.97% 48.44% 10.53% 53.68% 149226
Yasuo 52.39% 41.87% 10.52% 47.12% 242814
Annie 55.05% 44.54% 10.51% 49.75% 207493
Vi 54.28% 43.78% 10.50% 48.98% 258399
Darius 54.72% 44.22% 10.49% 49.43% 143617
Thresh 53.66% 43.18% 10.48% 48.53% 747150
Vayne 50.83% 40.35% 10.48% 45.59% 379347
Pantheon 54.80% 44.33% 10.47% 49.52% 274628
Graves 55.09% 44.62% 10.47% 49.81% 193827
Garen 53.60% 43.14% 10.46% 48.31% 122017
Diana 52.68% 42.22% 10.46% 47.43% 74122
Sona 57.63% 47.17% 10.46% 52.36% 154788
Ezreal 52.30% 41.87% 10.43% 47.10% 307483
Swain 57.20% 46.82% 10.39% 51.98% 61108
Quinn 54.77% 44.40% 10.37% 49.60% 64520
Udyr 55.57% 45.20% 10.37% 50.31% 335632
Shyvana 54.04% 43.68% 10.37% 48.84% 323633
Akali 55.84% 45.48% 10.36% 50.62% 152723
Gragas 52.31% 41.97% 10.34% 47.07% 79301
Zyra 58.70% 48.38% 10.32% 53.54% 105222
MasterYi 55.68% 45.37% 10.31% 51.36% 197507
Nami 56.18% 45.90% 10.29% 51.04% 156443
Leona 56.75% 46.47% 10.28% 51.63% 550002
Ryze 54.56% 44.30% 10.26% 49.39% 271738
Braum 58.22% 47.96% 10.26% 53.33% 93063
Leblanc 50.18% 39.92% 10.26% 45.11% 220880
Ashe 56.01% 45.77% 10.24% 50.89% 140299
Tryndamere 57.11% 46.87% 10.24% 51.97% 183790
Renekton 53.31% 43.10% 10.21% 48.22% 347800
Malphite 55.37% 45.17% 10.21% 50.18% 129486
Irelia 54.97% 44.78% 10.19% 49.88% 105519
FiddleSticks 57.72% 47.53% 10.19% 52.57% 119728
Corki 55.38% 45.23% 10.15% 50.27% 65902
Khazix 54.69% 44.55% 10.15% 49.65% 299274
Tristana 54.76% 44.61% 10.14% 49.62% 183186
Fizz 55.54% 45.42% 10.12% 50.43% 215390
Vladimir 52.22% 42.17% 10.05% 47.16% 74755
Katarina 56.57% 46.54% 10.03% 51.52% 180100
Jax 56.56% 46.54% 10.01% 51.61% 420357
Orianna 53.33% 43.39% 9.94% 48.37% 203849
Warwick 59.33% 49.40% 9.93% 54.32% 333202
Nocturne 53.00% 43.09% 9.90% 48.02% 245216
Lulu 54.31% 44.44% 9.87% 49.29% 193290
Twitch 55.07% 45.21% 9.86% 50.15% 337923
Janna 56.41% 46.59% 9.81% 51.42% 106945
Soraka 57.14% 47.36% 9.79% 52.22% 324054
MonkeyKing 57.40% 47.71% 9.69% 52.52% 269605
Lucian 56.07% 46.38% 9.69% 51.24% 612664
Zed 50.19% 40.55% 9.65% 45.37% 212769
JarvanIV 55.77% 46.14% 9.63% 50.94% 143599
Riven 53.96% 44.52% 9.44% 49.23% 215531
Evelynn 53.68% 44.25% 9.42% 48.90% 118944
Kassadin 55.96% 46.60% 9.36% 51.25% 121801
Taric 55.51% 46.21% 9.30% 50.77% 84396
Fiora 58.14% 48.86% 9.28% 53.48% 117399
Alistar 48.73% 39.62% 9.12% 44.04% 81495
Kayle 58.97% 50.21% 8.76% 54.55% 268477

By eye-balling this chart, I think it's clear that champions that are long range and/or heavily skillshot dependent (e.g. Jayce Nidalee Olaf Lux Varus Ziggs) have greater blue side advantage; on the other hand, champions with short range and few skillshots (e.g. Eve Kassadin Fiora Alistar Kayle) do not have such heavy advantage. 

One particular champion on that chart is Rumble. Rumble currently has slightly below 50% win rate overall. However, Rumble actually wins 57% of the time on blue side, and only 41% on purple side. This is roughly a 15% difference for Rumble on blue and purple side, far more than all other champions which hover around 9% to 11%. I believe the reason here is that Rumble's ultimate is a hard-to-land skillshot that has very long range. Due to the camera angle, it is far easier to aim Rumble's ultimate from the blue side than from the purple side.

Some implications of this:

1. You can make a champion look a lot stronger just by playing that champion more often on the blue side. Suppose a champion became FotM and he is always first picked - making this champion to be always played on the blue side. Then this champion's win rate will increase by 5% just by the blue side advantage. So, for example, if everyone decides that Ashe is strong and always first pick her, she will win ~55% of the time instead of her normal ~50% win rate. making her look a lot stronger than she looks. This hasn't happened yet and no champion has achieved 100% blue side appearance on ranked solo queue - even pre-rework Kassadin "only had" a 52% chance to play on the blue side.
2. It is demonstrated that blue side wins 10% more than purple, so if you can somehow "dodge" all purple side games without penalty, you will be climbing up in rating like crazy. So, for example, I can see that a player intentionally troll at champion select when he knows he is playing on purple (at champion select you already know which side you will be playing on), hoping that someone else on his team will dodge. This will give him a better chance of playing on blue side instead of purple.
3. The competitive scene is affected by this as well. So far,  Riot has dodged the question by claiming that the sample size from LCS games is too small to see its actual effect, but I think it's pretty clear now that blue side has an advantage after three seasons of LCS. If we believe that competitive games, similar to solo queue, also have 55% win rate on blue side for two teams of comparable strength, then playing on the blue side in competitive LoL is roughly comparable to playing as White on chess (http://en.wikipedia.org/wiki/First-move_advantage_in_chess). 

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