The institution of Judges, as described in the book of Judges, is an English translation of the word Shofet, a political position which doesn't really exist in modern times, and as such is often poorly understood even in the study bibles and commentaries that I have read. And yet, there are reasons to think that whether or not the stories themselves within this book are true or not, there really was a class of Shoftim prior to the monarchy. That, plus issues of chronology among the judges, get hashed out a bit. And also we talk about the fact that the bible really doesn't like to talk about Israel getting defeated in times when it is theologically inconvenient, yet was probably getting kicked around like a rented mule around this time.