The most common reading of Jacob 5 involves the history of the House of Israel. What follows is another approach to that allegory. This is not meant at all to replace the standard readings; it is just another approach.
Jacob 5 includes a contrast between tame and wild olive trees. The tame trees seem sure and steady, but they also prone to becoming listless, almost lethargic. The wild trees seem to brim with life and energy, but display a propensity to lack focus for that vitality. When the tame trees begin to decay, the Lord of the vineyard wants them to produce new life in the form of young, tender branches (Jacob 5:4). When this is only somewhat successful, the Lord of the vineyard determines to graft the tame branches with the wild branches (versus 7-8). What seems obvious from this is how the Lord of the vineyard seeks to keep the best of the tame branches, perhaps their good fruit and stability, and combine that with the vibrant energy of the wild branches.