Originally Posted by Robertroberto
I believe these matches occur when your clan has several nearly maxed TH9 bases and the opposing clan has several moderately rushed TH10 bases because the matchmaking system thinks they have similar score.
My clan has no rushed bases. We have several nearly maxed TH9s and we are often matched with 2 to 5 rushed TH10s where our #1 can be as strong as their #5 in terms of defence excluding walls and heroes, and they have the potential to 3-star our top bases easier than we 3-star theirs in terms of offence. (I would like to note that their middle bases aren't too bad as well.) On the other hand, we have never been matched with clans where their top bases are moderately rushed TH9s or mid TH9s, that's why I believe maxed TH9s have closer score to rushed TH10s than less developed TH9s.
Another hypothesis suggests if the difference between your clan's top bases and bottom bases are too wide ranged, your matchmaking choices are more limited to clans with similar composition as you, which could create unbalanced scenario as well. This isn't apparent in my personal experience but you can start paying attention to that as well.
If you want to get technical, you can use google translate to read this thread to see how people are trying to figure out how each defence theoretically weighs or this thread to see how people can exploit this system in practice.
