I changed my defense to just my hero 24 hours ago and I am already seeing the effect described by a lot of people above. I’ve only seen 2 fully traited khorvash teams and 1 bone dragon / manticore team, but all of those were revenge battles. Everything else is below 8000 in strength. 
This may not be how @Sirrian intended this to work, but from where I’m sitting it’s exactly how it works. Thanks for the great tip people, PVP is a lot more fun again.
whats ur def win ratio with something like that?
i need to know is it worth D:
im hesitating with the idea coz i wanna see a defense win sometimes 
3 wins and 14 losses so far this week. Pretty decent for a 1 troop defense I think. My fully traited Khorvash, Manticore, Valkyrie, Mab defense only won around 25-30% of its battles anyway, so it’s not a big drop-off for me. And besides, defense losses give revenge battles, so it’s all good…
So I stand corrected, at least partially. I started off the week playing about 200 Explore battles so the sample size is small but I set my defense team to one lone Sacrifice.
Defense team power rating definitely seems to have at least SOME affect on Invade offers. Out of 18 battles, I was only offered FOUR that had a power rating over 8000. That’s pretty much the inverse of my experience using a defense team with a power rating over 8000, where only 4 offers would be LESS than 8000.
That being said, there is also some other factor at play. I occasionally get offered matches that are quite memorable, meaning the team composition is so unorthodox it’s hard to forget. The number of those matches increased greatly after changing my defense team and the instances got more frequent the longer into my win streak I got. Bear in mind, these opponents were not flagged as revenge/rival, so there appears to be some correlation with winning streak length.
By the same token, the number of single-unit teams I was offered also went up dramatically.
I was offered only one hard match that had a M/M/DB/BD configuration. Coincidentally, this wasn’t just the only offer with this specific configuration, it was the only instance of Manticore or Bone Dragon in all of my offers.
My 2 cents on the subject:
I once tried the weak defense team strategy for a few days, and did not see any increase in easy invades. To the contrary, they were even harder on average.
Since then I stuck with the same ‘strong’ defense team for quite a long time, and as far as I paid attention, the difficulty of my invades can change dramatically depending on the day or the week or just randomly. I can have an easy day or week when all the defense teams I face are a joke, or I could have a day or a week when all I face are full mythic meta teams.
Based on my experience per above, there is no way to determine if changing your defense really makes a difference, since RNG tends to be streaky, and human beings tend to see patterns where none exist, especially when looking for them.
Certainly, that’s why I use words like “appear” and “seem”. It’s impossible to draw any concrete conclusion, so we can only report what we see.
Speaking of only reporting what we see, since posting that, I’ve been offered M/M/DB/BD three times in 6 matches. LOL
I’m a good 75+ matches in now and all I can say is that the results are definitely different. My average Hard invade has decreased 1000 points to around 7500. I get the occasional opponent over 8000 but it’s like 1 in 10 instead of 9 in 10.
Are you excluding any revenges as you tabulate that?
Yes, I just started playing PVP this morning, so I haven’t even had that many revenge battles yet.
Did anyone else’s invade team “fist power” increase or decrease when they changed their defense? I had a one card defense team (one mythic full trait khorvash lv 20) and my invade team’s fist power was 6900-ish. I changed my defense to khorvash manticore manticore manticore (my manticore is full trait legendary lv 19) and my INVADE team increased by approx 300 points, to 7200-ish, despite me not changing anything on my invade team at all…
Is there something I’m missing here?
This is because the game forgets to load the fist power of your mastery from guild statues. Fixes itself as you describe, change defence teams or play one battle, team fist power will increase.