When I read the books of Kings and Chronicles I am struck by the complete utter lack of "godly" kings in the northern kingdom of Israel. Israel batted a paltry .000 (0-20) 20 kings up and 20 kings down that's terrible even for an AL pitcher in Inter-league play. Judah on the other hand also had 20 kings throughout its history (including the crazed grand-child murdering queen - Athaliah) they batted a much better .350 (7-20) (Joe Mauer type numbers), but with only Hezekiah and Josiah receiving unqualified good reports (they didn't get caught taking HGH - to continue the baseball analogy). These numbers are staggering.
Were the 20 kings of Israel really that bad? And if so, what made them so wicked? Or to ask the question another way - what is the governing principle by which the author/compiler(s) of Kings and Chronicles judged the reigns of the 40 kings of Judah and Israel?
The governing principle is this - How did King _____ interact with Jerusalem worship?
Now of course each individual king's report should be studied for proper nuance of the character and actions of each king. However, I would argue that every one of the 40 kings is primarily judged on how they treated the worship of Yahweh in Jerusalem - not foreign policy, not civil rights, not even following the civic law. One might ask the question - why is it such a big deal to worship God in Jerusalem? Well the answer is quite simple - Jerusalem was the earthly home that the other-earthly Yahweh chose to have his name. That's a big deal!
One of the under girding themes of Deuteronomy-2 Samuel is the search for the permanent place for the establishment of the House of God (see especially Deut. 12:5). Throughout this period of about 500 years (ca. 1450-965 BCE) the tabernacle (and some of its pieces) travels across the Sinai stopping at various stops in the central hill country before finally arriving at its permanent home on the threshing floor of Aruvnah the Jebusite (2 Samuel 24, 1 Chronicles 21) under David and then becoming a full-fledged house for God under his son Solomon. From this moment on worship of Yahweh is only allowed in Jerusalem - the place of the first condescension (Yahweh dwelling in a man-made structure - a type of the One who would take on flesh Philippians 2:5-8) of the King of the Universe! This background becomes the lens by which the regnal (kingly) evaluators view the kings of Israel and Judah - and the reason why most of them didn't make the cut. In a way the temple in Jerusalem has a mediating effect for the Davidic line despite their flaws, but has a damning effect for the Israelite lines of kings who in spite of their sometimes good qualities are repudiated for ignoring Yahweh's clear decrees.
There is no better example than the first king of the divided kingdom of Israel - Jeroboam the son of Nebat. The first action which Jeroboam takes against Judah and Rehoboam was to establish new temples (Dan and Bethel) with new priests (outside of Levi) with a new religious calender and with a new/old representation (golden calves - one at Dan and one at Bethel vs. the Ark of the Covenant) (1 Kings 12:25-33). This clever geo-political ploy against Judah and Rehoboam (the Israelites now had no reason to go to Jerusalem and Judah) was an outrageous sin against Yahweh. To be sure this was not complete idolatry in the sense of rejection of Yahweh for Baal and/or El and/or Asherah - this sin was something slightly different. This was the sin of syncretism mixing some of God's transcendent, Yahweh-centered revelation with a lot of man's earth-based, man-centered theology. On account of this all of the kings of Israel receive the following epithet - "For he walked in all the way of Jeroboam the son of Nebat, and in the sins that he made Israel to sin, provoking the LORD, the God of Israel, to anger by their idols."
Personally, understanding this principle has been helpful for properly discerning the kingships of ancient Israel - especially Ahab and Jehu. The kingdom of Ahab is the wickedest of them all because it confronts and tries to replace the syncrestic religious system loosely tied to Yahweh (which flawed as it was still had a mediating effect for Israel - consider the fact that they existed and sometimes prospered for 210 years) with the complete and utter apostate system of Baalism (switching teams is an understatement). Conversely, the kingdom of Jehu properly carries out the will of Yahweh in purging the Ahab dynasty and the Baal cult - for which he is commended - but he still continues the syncretistic sins of Jeroboam, which ultimately lead to his line's demise.
All of this means that the standard of Yahweh does not change - relatively lesser sins (complete idolatry vs. "just" syncretism) do not win approval - the Judge of the Earth is not swayed by man's relative ideas of justice.