If you've ever played a semi-collaborative game, like Tarot, Belote, Not Alone…, where teams face teams, maybe you've encountered this issue, this frustration in the elo distribution, that you've made a "tie" (with your Partner). It's quite an elegant solution to adapting the elo to (semi) collaborative games, and it does work, up to a certain extent. But there are 2 problems.
The 1st one is a very tiny one, it's that you would normally expect that you won (your team did), not that the game ended in a draw, which it did not. But, well, why not.
But then comes the elo distribution problem. The problem is that it's not totally fair, especially in the instance where you team with low elo players. In this case, especially in Not Alone where you're many to team together, you're about to win very little, or even worst, to lose elo in both cases of victory or defeat (because you tied with many players you "were supposed to win over" - though you could not actually in this game - and that counterbalances the winning against only one player). That makes totally no sense.
The solutions for this are, first the status quo and hence not to play with low elo players, but that's a bit shameful to incite players not to play, especially in BGA where it's about to play a lot (and ty for that, I truely enjoy BGA),
second to adapt the elo system here in case of team vs team.
I'm no mathematician (though I do like mathematics), but idk, an idea could be, roughly, to create a special elo system for teams games, where you would be considered a (contextual - for one game) team, and elo would be sumed up and averaged within teams, then the calculation would be between those two elos, it would determined the sum to share, and then the share would be according to elos, (sth different than elo actually if you think of it; that's a big point, that's even an issue, but after all even the current team elo system is, to me, not exactly an elo system, at least is an adaptation). So at least it would remain positive or negative according to the outcome.
Well, any solution, but at least sth to prevent competitive players from running away from in particular Not Alone which barely supports any form of competitive playing in the long run (I mean seeking for ranking) - just need to look at the rankings, best elos are at 300. which virtually no other game has the like of.
Hope I made my point clear.