A team should be able to perform better than the sum of its parts.
You cannot simply throw some people in a room and expect them to work effective from day one.
So what can you do?
It turns out all teams have to go through a bunch of stages before they can start performing for real. And no, you can't skip any of these stages. Sorry.
The goal is to reach the last stage, the performing stage. This requires effort and persistence from the organization. In practice, few teams leave the storming stage.
As soon as the team does something wrong or some conflict arise, the organization tends to "step in" and fix the problem, by splitting up the team or putting a leader in place so it won't happen again.
What happens now is that the team become dependent on a single person for decisions, so they never really work out their kinks. This effectively blocks the team from reaching the performing stage.
When the team composition is changed (a split for instance), it gets pushed back to the forming stage again and the cycle repeats itself. How ironic is that?
This Happens All The Time
I see this all the time, teams that begin to perform gets broken up
So stop interfere with the team!
Instead, bring in a someone with agile coaching skills. This is a type of leader without decisive power whose goal to to help them improve their skills and show them how to fix their own problems.
I cannot emphasize this enough: Growing a powerful team costs in the beginning, but you make up for it in the long run.
A team that survives long enough to reach the performing stage is much more productive than your ordinary group of people sitting in the same room.