What complexity tells us is that we can't predict with accuracy about complex systems. But not all aspects of a complex system are complex. Furthermore, there are things that influence complex systems. The key is feedback and shortening delays in workflow and in achieving feedback.

But Scrum makes many predictions:

1.  small batches are good
2.  cross-functional teams are good
3.  daily corrections are good
4.  retrospections to see where you are are good
5.  collaboration is good
6.  and many more

The thing is, however, there is a model under Scrum, called Lean, that will help you see what improvements will be. See my next post for what we've been using for a long time and which you already know (intuitively anyway).