You know what I didn't like about the old system? People used to say that 60:40 would mean that out of 10 matches, you would theoretically win 6. This implies that Brawl's MUs are like 10-sided dice, with 60:40 being 6 "A" faces and 4 "B" faces, and that playing the match is no different than rolling such dice. Did the members who explained the system before realize that all they're saying is that match results are up to chance? From what I remember seeing in matches and hearing from other people, there comes a time where a player gets so good with his character he never loses to the other side of the MU. Is this a theoretical fallacy, since the MU was supposed to be 60:40? Why can't the opponent win 4 out of 10 matches in this case, if the MU is 40:60 against him? Even with equal skill level, matches are not decided by chance, but by a buttload of many different factors, and I know lots of you people know some of them (player skill, character choice, stages, rules, player's state of mind/health, how the MU is being played, etc).
This new system both simplifies the old faulty ratio system, and condenses it all in 9 MUs: -4 < 0 < +4, having similarities to 0:100 < 50:50 < 100:0 but not enough to make an accurate comparison to it (+1 =/= 55:45 or 60:40 for example, we're using a system of our own creation with our own definitions and limiters, but you could say that +1 feels the same as 55:45, 60:40 or something around those). If you're trying to actively compare both -which you shouldn't-, +1 will be up to your own interpretation of what it means in the old ratio system, because we did not make this system to mirror the old and instead be more precise.
There will be MUs that feel easier or harder than others in the same tier, but from our discussions when resolving these discrepancies, we decided to categorize them under the tier they were closest to. If there was an MU which was +2 or +3, but no one could decide in one go what it would be, then we had to discuss it out to find where it's more closely related to, and we would also ask external sources on the matter. Some of you were probably used as external sources, but it wasn't a secret and we told you guys it was because we were working on an official MU chart. We DEFINITELY used your input and counted it as if it was from another BBR member, so your voice had a lot of weight. A small number of external sources even had more weight than BBR opinions because we recognized that they were more knowledgeable than us in that topic and that their opinions were much more valuable than ours.
There will be disagreements on the final result, but I ask you this: is there a way where we can come up with an MU chart that no one disagrees with? There's no concrete proof on how MUs are supposed to be rated, so it is all opinions from BBR members and top players of their respective characters. And as with opinions, not everyone agrees with them as easily as one can agree to things like 2+2=4, or things like the earth orbiting around the sun, which all are true and have 100% undeniable proof.