A group of us (some engineers, some maxers) have been having a pretty good discussion about how to avoid seeing a constant barrage of Engineered opponents in war, and to almost always get fair and competitive wars. Keep in mind, this is not the place to read if you want to get "easy" wars. If you follow these guidelines you will run into clans with permabased 30/30 hero th9's, 1000++ war stars on every person in clan, lvl 12+ clans, etc etc, more often than you were before. However, what you won't run into is clans with a 40/40/20 th11 and a max offense defenseless th10 sitting at the bottom of their war roster in a th8/9 war. Every war, or almost every war, will be determined by your skill in attacking and building solid war bases, and by your opponent's skill in the same areas.
1. Keep a tight spread of th's - But not too tight. If you want to match with a comparable opponent, then you want to have a war roster that is relatively similar to a bunch of other clans. A good rule of thumb is to try to stick to around a 3 th spread on your war roster, though the actual power of the bases matters a lot more than the specific th level of each base. I have personally seen a huge number of fair and even contests when running th7-9, th 8-10, and th9-11 wars, though generally slipping in a new th 11 in an 8-10 roster or a high 8 in a 9-11 roster doesn't cause issues. Certainly there are other typical war roster compositions, as well. Skrags has a good discussion about this topic in post 210 of this thread, here:
2. Balanced bases - mild .5 upgrading by starting with a few key offensive troops, or getting your queen to 5 or 10 is fine, but once you start getting real offense at the new th then you need to start working on your defense. Failure to do so causes issues with your balanced bases checkbox in the mm algorithm.
3. Don't dump low th's at the bottom of your roster. This puts you into the full on "unbalanced war roster" category. Ie, the mm algorithm views you as roster engineered and includes you with the other engineered clans.
4. Recent war record really matters: as you win more and more, you get a progressively more-punitive war weight penalty. Eventually, in every clan that I've ever been in, this gets to the point that you start matching up with engineered clans, or just regular clans that have a clear advantage on paper over you. I've been extremely active in 3 different clans, one of which has gotten as high as a 50 win streak, and believe me when I say that you'll eventually run into an unwinnable war matchup unless you heavily engineer. I, personally, war to have fun and compete, and I think that most people in this game are of a like mindset. But if it's just all about winning to you, then this is the wrong thread.
5. Restart your war search every 30 minutes: the longer your search takes, the more relaxed the mm algorithm gets on the parameters for your opponent. I have never seen an unwinnable war that hit in under 30 minutes, and the vast majority that I get that fast are extremely even and fair..ie, fun. - I must mention here that a close friend of mine was personally told by Jonas that restarting war searches has a "minimal" impact on your war matchup. However, "minimal" is quite subjective, and sometimes it doesn't take much relaxation of parameters to allow a well-engineered clan to slip into your pool of prospective opponents.
6. Do not permabase. To the war mm, a fully max th9 looks the same as a 9.5 that wasn't quite fully maxed at th9 but has sf and a couple of troops upgraded. If you have a very large number of "max" bases at a specific th in your clan, then the mm will break its arm patting itself on the back while it matches you with a bunch of .5's from the next th above. Can you get away with a fully max th9 or th10 here and there? Sure, if only one or two of you do it, but be careful that half your clan doesn't camp at that level. If you find your clan in this position at present, then perhaps consider moving a few up to the next th level. Remember, an early .5 doesn't count as unbalanced, it's only when you start maxing out offense/heroes without upgrading any defenses that the mm starts viewing you as unbalanced.
Keep in mind that going a bit outside of these parameters is usually ok, but the farther you stray the more likely you'll be to get an unbalanced war. Including a th 6 or 7 in a th8-10 war is usually ok. Including a couple of 8.5 or 9.5 is usually ok. Letting search go for 45m or an hour instead of 30m isn't terrible most of the time. However, if you get lazy or careless and do all of those things, every time, then you're significantly increasing your chances for an unbalanced war (might favor you, might favor opponent). Also, the longer your war win streak, the more war weight penalty you'll get, so if you get away with going a bit outside of these parameters and still get a clump of fair and competitive wars, that's not guarantee that after winning 5 or 6 in a row you can still do that and get another fair and competitive war on #7.
The above are my own thoughts on the subject. Additionally, Chief Tuck, Denton and others have added much to the conversation, I'll link their posts below:
Denton linked most of this in post #53 here: https://forum.supercell.com/showthre...=1#post9165547
We are hoping that this thread will help to answer a lot of questions that people have when running into a slew of Engineered opponents, and, hopefully, will help the community to get more-balanced and fair war matchups going forward. Or, at the least, it will help you to understand why you're getting the matchups that you get, and allow you to make a decision from there about whether you want to continue getting those matchups or make changes to prevent them in the future.
This thread kind of got a group of us started on the conversation: