I have clearly gone mad: I have buffed the already-OP Purple Caster Minions.
As many of you may know, Blue Side tends to have a higher winrate than Purple Side. I’ve updated the Balance of Power system to add an appropriate adjust to point values. This change will largely neutralize the Blue/Purple factor.
This is actually a good illustration of the principle behind the skill adjusts. I’ll run through the logic of the Blue/Purple adjust; the skill adjusts are very similar in theory, though their computation is much more complex.
- In Normal 5v5 matches on Summoner’s Rift, Blue Team wins about 51.9% of the time.
- Curiously, the disparity is much higher in Factions: Blue Side tends to win about 58% of the time, over all Factions matches in this arc.
- This may be because different factions have different rates of ending up on Blue Side. After some thought, I’ve decided to go with the universal value, as I can’t think of any good reasons why Factions matches would be more dependent upon the Blue/Purple difference.
- Taking this statistic at face value, it would appear that all else being equal the Blue Side will win 51.9% of the time. That’s a problem, because it means that every time someone creates a game for their faction and takes Blue Side, they’re gaining an unfair advantage. (No blame there: if they gave the other side Blue, they’d be giving their own faction an unfair disadvantage.)
- So, the scoreboard will now multiply Blue Side win values by (100% – 51.9%) times two, which is about 96.2%. Similarly, Purple Side win values will be adjusted by 51.9% times two, or about 103.8%.
- Let’s say Ionia and Bilgewater play a hundred matches, Ionia always getting Blue and Bilgewater always getting Purple.
- Everything else about them is equal, and (for this example) let’s pretend that both sides have the exact same level of strategy for using their roster.
- The only difference is side: Ionia always gets Blue, Bilgewater always gets Purple. We’d expect Ionia to win about 52 matches, and Bilgewater to win 48 matches. At base value, that means Ionia would gain about 260 points and lose about 240 points. The net result would be Ionia 20, Bilgewater -20, purely due to side differences. That’s not good.
- However, if we multiply Ionia’s wins by 96.2%, they end up gaining 250 points, and Bilgewater loses an equal amount. If Bilgewater’s 48 wins are worth 103.8% of normal, they end up gaining (and Ionia ends up losing) 250 points.
- In other words, with the adjust applied, both factions would come out of these 100 matches with 0 net points:which is how it should be, if they’re truly identical other than side choice.
Room for improvement?
I mentioned above that while the overall League winrate for Blue is only about 52%, it’s more like 58% in Factions. That might be an anomaly due to a small dataset or some kind of variance in the number of matches started by each faction, in which case the standard winrate is the one to use.
However, there’s reason to think that Blue may genuinely be stronger in Factions. Blue side presumably has a positive correlation with match-starter. The person who starts the match not only gets to pick their opposing faction, but is perhaps more likely to have a few friends on hand who know how to play together. If Blue really is stronger in factions for these sorts of reasons, then using the factions winrate would make more sense.
The trick, of course, is performing the necessary empirical research to figure out which of these intuitions is correct. That’s something I’ll have to save until later, when I have a bit more time.
Skill adjust works the same way, except that instead of Blue/Purple winrates, we use the observed winrates of various skill matchups, like “a Diamond and four Silvers vs. a Plat, two Silvers, and two Bronzes”. As with the skill adjust, this change will help ensure that gains and losses on the Balance of Power represent real differences in faction strategies and strength levels, rather than who has the most high-Tier Summoners or who gets Blue Side more often.
Note: the adjusts are a little different for the Howling Abyss and the Crystal Scar. I’ve updated the Balance of Power appropriately.