kmote has a great answer...
Specifically in sensus plenior God chooses elements of actual history that can be told in such a way that a hidden picture of Christ can be included.
For instance, church tradition says that the thief on the cross who asked Jesus to remember him was on the right because sheep are on the right. The tradition is ambiguous when applied to an orthodox cross because right is different depending which side you look at it from. The importance is that which ever side is pointing up is the right because of the imagery.
The scriptures do not tell us which side he was on. Why? Because he was probably on the left and including the detail would spoil the shadow. Crazy details are included because hey are a part of the hidden picture of Christ.
Shamgar - sword... which is the word.
son - builder
Anath - answer
slew - also means lame, contrite (Jesus had a limping side when his flesh was made to humble itself before the will of the Father (bruised heel, withered thigh)
Phiilistines - sojourner
six - tesimony of the Trinity in heaven and on earth
hundred - church
ox - priest
goad - root of 'teaching'
In one of the four senses it speaks of Christ being humbled.
In another of the senses it speaks of the church.