Sounds very interesting indeed, but also seems like there's a lot of potential for numerous civ wins if players go for a lot of top+bottom civ pairs..Hereby, I propose a new system which I named PairMinator (TM):
When people want more variety to civs, they mainly want to see civs that are used less in tournaments. What I propose is pairing up civilizations according to a consensus ranking similar to the one in Escape Monociv cup. The best civ gets paired with the worst, the 2nd best, with the 2nd worst, and so on. When players draft, they draft pairs, instead of individual civs.
Bo5: Each player drafts 3 pairs, for a total of 6 civs to be used for each player. For Bo7, its 4 pairs, for Bo9, its 5 pairs.
Why is this good?
First, each player will have one extra civ compared to the number of matches. That means, that unlike a regular 5 civ draft for a Bo5, where at the final game, the players would be aware of what civ the opponent will use, here, there is some unpredictability that requires more strategic thinking from the players to have the most appropriate civ matchup.
Second: There is the big decision and potential drama (in a positive sense): will you use your strong civs early, but then left there with weaker civs at the end when it matters the most? Or will you try picking one of the weaker civs early, pull an upset against a stronger civ, and then unleash your strong civ on the weak one in the end?
Third: Map-civ synergy. Unlike drafting individual picks in any system (mirrors, pool-based, etc.), where you dedicate a civ for a certain match (e.g. you pick mayans specifically because you want to play it on Reg Fortress), here you have to do smarter thinking both with map and civ drafting, since picking one civ that is great for a given map will also result in another civ belonging to you, you will have to draft map combinations before the civ drafting appropriately.
Fourth: A lot of different approaches. You might think that the first and last civ combo is not neccessarily worth picking, and you pick a combination that is having two "average" teams, so you have a balanced civ pool. Or you could go for the #1 civ with the last, gambling to win the early games so you dont have to use it.
Fifth: Works with different civ lists, pairs. Bored of the pairs? You can mix it up in any way you want, leave out a few civs from pairing (e.g each day has 5 civs banned, rest organized into pairs), and so on.
Overall, the varieties are endless!
With some way to reduce this possibility I think that would be a very elegant solution