solution for matchmaking and defenceless engineered bases in war
It can be annoying when the enemy's #23 wipes out your own #3 and #4 TH10s, especially when he has no defenses but his high level heroes and big cc still present a significant challenge to the TH7 he's paired off with.
My understanding is that the matcher calculates each base's defensive strength and offensive strength, and adds those together to determine an overall score. If you hit like a TH11 and defend like a TH2, you might be considered TH7 or TH8.
My suggestion is to calculate the defensive and offensive strength of each base, and then discard the lower score, using only the higher score to rank the base. If you hit like a TH11 and defend like a TH2, you'd be considered a TH11. There would be no more engineered bases. This would make for better-matched wars and encourage people to upgrade their bases more evenly.
The problem with my suggestion is that it discourages diversity. For example, people might resent being 'forced' to max everything before going up a th and they'd be discouraged from making .5 bases.
For this reason I also suggest an indicator on your profile to show how your offensive score compares to your defensive score. This way, you could go up a th to gain access to, or an upgrade to, a certain unit, and see that doing so doesn't skyrocket your offensive score (so long as you don't upgrade all your army camps and/or build a hero). Players should never know the algorithm used in matchmaking, but it would be great to have a visual indicator that shows how balanced our offensive/defensive strength is or shows us that our .5 bases are not a detriment to the clan in terms of matchmaking.