Nicholls has not been a universally applauded pick for New Zealand since his debut two years ago when he made a resolute half century against Australia at Wellington.
He has lacked consistency at times and has been guilty of frittering away opportunities, none more starkly than when he lashed out needlessly at Bangladesh's spinner Mehedy Hasan on 98 in Christchurch last season.
It cost him a maiden hundred. That did come, and impressively, against South Africa in Wellington two tests later.
But when he has fallen prey to rash judgments, other names get worked about. Why hasn't so-and-so been given a chance? There's a suspicion that the depth of New Zealand middle order batting mightn't be as strong as some like to think.
That's why you have selectors. They back hunches; they don't always get them right, but Nicholls has been persevered with.
The last three hours of his test batting life have been proof that the selectors are on to something.
The rider to that is it's time to ditch the scatty moments and make the most of every test opportunity.
You wonder if that time at the crease with Williamson in this test, might yet help push Nicholls' output to the next level.
After all, he could scarcely have had a better case study than his skipper.