Everyone has to agree with this, but there are also some players who are better generally at teamplay than others.
There are good teamplayers, and bad teamplayers. But it's not so easily classified. A good team is 37% chemistry 49% skill and 14% playstyle. My playstyle is made to own an attacking player while it just sucks againts a defensive one. Of course it's easy to beat an attacking player if you just run away and leave seeks to the corridors, but again it's more complicated than that.

The best teammates for me are my brothers and kind persons that dispite of the fact that they are much better in JJ2 than me, they still do what I ask them to do.

When playing with r3p...

R3p: e1, 1
Sucer: r3, die! (not preferable in this situation)

And then without having to wait two minutes, r3p dies immediadly, get's C or gives further advices.

When playing with Mave...

Mave: 1 go r
Sucer: r3

I wait for one minute meanwhile which the opponent comes to the base and hits me and goes rts.

Sucer: DD
Enemy roasted Mave
blue team scored a point
Mave: And you just possibly couldn't say DD erlier
Sucer: Please die on time
Mave: No!

So chemistry and playstyle do a lot in 2vs2. Some people's playing style fits to most personalities and strategies meanwhile others don't.

Back to the topic

If the lower bracket is played, can me and Happy replace a forfeiting team?