The reason 8 man scores are so lopsided is because of the field size. They shorten the field so you're almost always in 4 down territory, yet they keep it the same width. The width is the biggest issue, it makes guys have to cover the same area as 11 man, except you're missing 3 help defenders that you can push people back to. This just amplifies the talent difference between players. Hopefully that makes sense. Think of having the same size basketball court for space but only playing 3 v 3.
As for BGM, they haven't been doing anything that they haven't been doing for years. It's not like this is the first year scores have gotten out of hand, and its also not just them doing it to teams. Looking at stats in most games they do a good job of running the ball. That's the easiest way to prevent blowing people out, keep the clock moving. The second thing, which they do not appear to be doing well out is getting the ball to several guys. Usually they have 3-5 ball carriers, which isn't awful, but it could be improved. Part of that though is there are games that BGM only runs about 20 offensive plays because they just all work, it's hard to help that.
Look at some other top teams biggest wins (random teams).
Denver vs. North Tama: 6 different rushers 1 pass attempt (63-13)
Mount Ayr vs. Martensdale: 13 different rushers 1 pass attempt (63-0)
Lo-Ma vs. Griswold: 9 different rushers 3 pass attempts (63-14)
West Sioux vs. Gehlen: 9 different rushers 13 pass attempts (48-0)
BGM vs. GMG: 6 different rushers 6 pass attempts (81-0)
The numbers aren't actually THAT bad considering GMG had 4 fumbles and threw 2 pick 6's, but it's hard to know what's going on with the defensive substitutions without being there watching.
I still think BGM coaches could do a little better limiting the scores while not asking their players to take plays off, it's just not as bad as it looks sometimes. It's the people that come on here with poor arguments of "stop us" "get better" that really put a smile on faces when BGM is on the other end of the scoreboard.