Ardern and her ministers made plenty of mistakes in the first half of her term and the National Opposition was quick to expose them.
The second half of her term has been different. She is in control. Her handling of the Christchurch tragedy is part of the story but not the whole story. She had been improving every month before then.
Ardern has scored nine out of 10, as has Kris Faafoi, a minister outside Cabinet.
He is a shoo-in for promotion to Cabinet in the reshuffle the Prime Minister promised would take place some time after the Budget.
Faafoi, a former journalist, didn't exactly make his mark in Opposition, where he worked as a press secretary before winning the 2010 byelection in Mana.
But he has handled Commerce and Consumer Affairs and Civil Defence smoothly, addressed loan sharks and wheel clamping, taken charge in civil defence emergencies, communicated well with the public and taken on additional workloads after the demise of former ministers Clare Curran and Meka Whaitiri.
Ardern does not have an over-supply of excellent ministers but five of them have scored eight out 10: Deputy Prime Minister Winston Peters, Finance Minister Grant Robertson, Environment Minister David Parker, Agriculture Minister Damian O'Connor and Children's Minister Tracey Martin.
Three high-profile ministers scored the lowest mark of four points: Phil Twyford in Housing and Transport, David Clark in Health and Shane Jones in Regional Economic Development.
Twyford is too senior to be dumped from Cabinet but with major problems in the progress of KiwiBuild and major woes at the NZ Transport Agency, he may have to lose one portfolio.
The chairman of the Transport Agency, Michael Stiassny, resigned suddenly last week, just one year into a three-year appointment.
The first of head of KiwiBuild, Stephen Barclay, resigned in January after beginning only last May.
If the Prime Minister appoints any new minister in the reshuffle, and that is not certain, the most likely prospect is Whakatāne-based list MP Kiritapu Allan.
If Ardern decided to appoint two new ministers, Mt Roskill MP Michael Wood could be a contender after his impressive work chairing the select committee on gun reforms.
• The ratings are out of 10 and reflect a judgment about three factors: How effective the minister has been in delivering the Government's policy; how effective the minister has been in representing the Government to the public; and how valued the minister is to the Government.