Chapter 2 tells us how to read the rest of the book. It is the theological framework for, or interpretation of, the stories that follow. It sets up the following cycle:
2:16 mercy and deliverance
2:17-19 the cycle is repeated (and gets worse)
The first story of a judge (Othniel in 3:7-11) is a rather colourless story that seems design to illustrate this cycle:
The cycle, however, can be broken down into two parallel movements of ‘moral symmetry’:
human disloyalty -> divine judgment
human repentance -> divine mercy
We see these two divine responses repeated throughout the book of Judges.