In my opinion, the higher you are up in the rankings, the less risks you feel you can take with every test match, particularly those that sit close to you.
With the way the weighting works, it can be detrimental to your ranking if a team well below you beats you (and the opposite for beating a team well above you).
Interestingly, with NZ now sitting 3rd, these consecutive wins against number 1 carry extra weight.
When England sat in 3rd don’t have much to lose so giving their players that exposure and experimenting outside of major tournaments is not too risky to their ranking and pays dividends for giving their players experience.
I predict at the next review NZ will likely be back to 2nd, especially if England have some losses against Jamaica.