Master Vintner Blog on stirring
Stirring is a big deal in kit wines. First, the water you add needs to be mixed well, and concentrate and water take a bit of effort to blend.
Second, for the wine to clear effectively you need to stir the wine hard enough to degas it. Stirring rods and drill-mounted whips are excellent aids, but you can do it with a spoon if you stick to it and put your back into it.