The issue isn’t mixed strengths really, it’s usually because of a super casual Free for all approach to the war itself.
That said it is hard to make a more casual alliance less so but even going as far as having 2 target times to hit will help.
We have 3 dedicated cleaners in our alliance. They have taken on this role because they don’t have the mega deep bench that others do.
So when we are getting to a smash time they will be around to mop up the misses. A lot of alliances at our level clean there own so already we are punching above our weight but for us it works really well and we win more than our fair share.
Those with smaller rosters will of course despair if all they have is 6 4800+ defences but if it’s done well that’s because no one has missed yet and they can just hang on to there hits for later.
I was in a super casual FFA alliance and we really would have people rock up, smash the 6 little opponents and then that’s them done. A massive waste of flags and frustration for all. In the end it got to the point where I couldn’t do it anymore and I moved up. I’m not advocating people to leave alliances but I am advocating for people to try and change the workings of an alliance if it’s a bit of a shambles.
My 2 cents anyways