Firstly I am not affiliated with supercell and do not have access to game code; just a simple CofC rainman who is unsatisfied with matchmaking. I lead several war clans from ranges of levels 50+ to levels 100+. I have seen clan balance in war come and go. I hope that by posting a statistical analysis of war matchmaking that players and developers alike will be able to understand and improve on game mechanics.

"So we appear to be in a rut of unbalanced war matches lately and no one likes ruts. Basically this is because there are not many clans similar to ours (number of th10, th9, th8 & th7). CofC tries to match us with an equal clan, but because there are so few other clans that are our equal we are being randomly matched with clans that are significantly stronger or weaker. In contrast, the composition of th10, th9, th8 & th7 that we had around one month ago was very common and we were finding very balanced matches and thus winning because we are awesome. The below diagram illustrates this theory. The left square is our current range of matches. The colored circles are opponents. The game randomly picks a match from our range of opponents. The right square is our old composition. It is an algorithm which takes the geometric mean (assigning low weight to outliers) of the sum of our members' average building/troop/spell levels. This gives us a number and we are paired with a random clan from a range of other clans NEARBY (rarely equal to) that number. "

"Tonight we had a very long search for war and finally found a pretty wonky match (40 th10 vs our 13 th10). I have made another graph to explain how matchmaking works using an iterative algorithm (again, in theory). On the left is the time it takes to search for a match. On the bottom is relative clan strengths (cumulative building/troop/spell levels) with us at a middle strength of five. Every few minutes of the search where no opponents are found in a nearby strength range, the range expands and the search starts again. Eventually after 30 minutes of iterations we are searching a huge range of clan strengths and matched with the first possible opponent, who is most likely to be far too strong or far too weak since they were found in the last iteration. One simple way to abuse this algorithm is to cancel the search after 5-10 minutes and just try again later."

"Finished a plot that illustrates why we are encountering too weak or too strong matches recently. Note the recent dramatic increase in number of th10 and decrease in number of th7. This makes us very unbalanced and the matching algorithm for wars may only work well for ideally balanced clans. The flat green line represents the trend of our composition a few weeks ago during a solid win streak. The high slope red line represents our current composition."

Update: After several matches using my suggestion, we have only seen balanced matches. Went from consistent totally unbalanced matches (40 th10 vs 13 th10) to consistent matches with almost identical clans. All the "solutions" for future updates are amusing, but this is the only functional method of finding a good match if you are having balance problems.

Update:Dozens of matches later, using this method we have not experienced a single mismatch.

Start search, wait ~10 minutes, cancel and restart. This prevents the matching algorithm for searching for clans far out of your range.

Note: Attaching a relevant quote.

For your purposes common refers to low level.

Developers have stated that clans trying to recruit a few very low level players into their clan to reduce their opponent levels are "shooting themselves in the foot." This implies two things, first they are likely referring to a geometric mean code line in matchmaking (extreme outliers hold little weight) second thattherefore your one very strong player weighs little as well. In my opinion this is an extreme advantage to your clan in war.

In order to explain what kind of TH levels you should look for, I would like to break down the geometric mean coding that I suspect SC is using in matchmaking. I will assign an abstract value to "player strength" where a developed th9 is stronger than a midrange th9 which is stronger than a fresh th9.

Player StrengthTH Level10 Developed TH10 9 Midrange TH10 8 Fresh TH10 7 Developed TH9 6 Midrange TH9 5 Fresh TH9 4 Developed TH8 3 Midrange TH8 2 Fresh TH8 1 TH7

Analysis-You said 1 Developed th10, 4 developed th9, 4 midrange th8, 1 th7. Mathematically this reads: geometric mean = (10*7*7*7*7*3*3*3*3*1)^(1/10)=4.3 ( Slightly above Developed TH8)

I interpret this to mean that when your war match is calculated you are searching for a clan whom are also slightly above developed th8 when averaged (this could be a clan with a wide spread of th levels like yours, or a clan of 10 fresh th9 or maxxed th8). Recruiting strong th8 and 7 will thus bring your strength down, resulting in matches with more common (low level) clans and vice versa.

Note- The matching code uses (probably) an iterative algorithm along with geometric mean. If the search runs longer than 5-10 minutes you will likely be paired with a significantly stronger or weaker clan. This is explained in the OP. To prevent this,restart the search after 5-10 minutes.

Note2-Hearty congratulations if you read and understood any of this.

Update:Several clans have reported very unbalanced matches from very short search times, this is why.

It is important to understand that a maxxed th8 can have the same strength as a premature th10, and a clan with 50% th10 and 50% th8 may have the same strength as a clan of 100% th9.

Update:Proof of concept of geometric mean; that adding low levels to find weak opponents is "shooting yourself in the foot."

Originally Posted bySuperSteve{SuperCell}Update:

Some random speculation:

Update 11/12 In regards to potential fixes in search algorithm:

Update 11/13 potential fixes in search algorithm: