From Walter Brueggemann’s Theology of the Old Testament:

By focusing on this material, we immediately center on David, the “star” of Israel’s narrative, who pushes Israel’s storytellers to imaginative extremes. More than this, the text as we have it suggests that Yahweh is inordinately and irrationally committed to David. This uncommon commitment causes Yahweh to act in odd and unreliable ways. That this inordinate commitment can produce odd actions in Yahweh is itself an important theological datum in Israel’s cross-examination. It is as though when David enters the stage of Israel’s activity, Yahweh’s characteristic features of sovereignty and fidelity are strained and challenged. What interests us here is the awareness that the entry of David into the story can skew Yahweh’s way of being available to Israel. This skewedness in the direction of David can produce, as a downside, the sense of the tragic in the story of Saul, who never really had a chance in Israel’s imagination. Being juxtaposed to David, and given Yahweh’s peculiar attentiveness to David, Saul is the wrong man at the wrong time. But the wrongness is not given as a public, political datum—it eventuates only from Yahweh’s peculiar affection for David.