If two good players pair together I can see how it can severely influence the outcome of a game, provided the matchmaking doesn't account for it. Right now it definitely accounts for a good player, especially ranked, in that it tries to make up for it by pairing the weakest players with them (especially that one player that doesn't press recup and will anchor the game).
How will it go when 2 players are paired together? I don't know but if nothing changes, 2 ranked players in a duo will probably literally get all the weakest players in their team, but if this is 2 good unranked players, then I don't know. That's why I came up with the idea multiple times to have the matchmaking only field a dual premade if there is another in the other team, but idk. We'll see I guess?