Ross Taylor, ranked third in the world among ODI batsmen, averages a monstrous 71.31 since the start of 2017, and has scores of 82, 69 and 93 from his last four completed innings. Martin Guptill, ninth in the world, averaging more than 50 since 2017, has two hundreds in his last five outings, and the biggest ever World Cup score. Kane Williamson, 13th, hasn't been quite as prolific in the last two years, but still averages 43.35, and arguably has the most solid reputation of them all.

But what about the batsmen that come afterwards? Tom Latham, James Neesham, Colin de Grandhomme and Mitchell Santner have serviceable averages through the same period, ranging between the high-twenties and mid-thirties. But in the context of a World Cup in which the best teams have the likes of Jos Buttler, MS Dhoni, Kedar Jadhav and Ben Stokes operating through the last 15 or so overs in an innings, does this constitute if not a bona-fide weakness, then the makings of one?

In fairness, it is not often that New Zealand's three best batsmen fail collectively - they have played 89 matches together, and in only 19 have Guptill, Taylor and Williamson not managed 75 runs between them. And yet, the team's performance on those occasions drops substantially. As opposed to an average score of 289, they muster only 214 when the Big Three produce less than 75. More importantly, the win percentage suffers. New Zealand 64.71% when at least one of their best batsman are rocking it; 26.32% when all three are not.

The issue, of course, is only really in focus in light of the mini-collapse against Bangladesh. They had been cruising to the target of 245 at 191 for 4, before the wicket of top-scorer Ross Taylor prompted a stutter. They lost four wickets for 47 runs through that period, before eventually, Santner's 17 off 12 balls took them home. No. 10 Lockie Ferguson was still forced to bat out three deliveries in what had suddenly become a tense finish, however.

"I think, if we're honest with ourselves, if you look back at the Bangladesh game, and the position we're in - we probably should have been walking off with a six-wicket win or something like that," coach Gary Stead said of that match. "But strange things can happen in cricket. And I'm just thankful we were on the right side of it and got the two points."

Perhaps New Zealand feel the reintroduction of Henry Nicholls, now fit, could stabilise the middle order as well, though there is also a chance he may be deployed as an opener. "Henry's one guy that we think can cover different bases for us," Stead said. "We've got part of the squad that was selected is making sure that we've got people that we can pull in and out at different positions. That will depend on what we think is the right balance, against different opposition on the grounds."

It would seem unlikely that Afghanistan possess the weapons to expose New Zealand at Taunton, particularly on what will likely be a green-tinged surface. Those with local knowledge suggest that grass on the pitch does not necessarily mean anything, given the ground's reputation as one of the higher-scoring county venues in the country. But what this surface may do is partially neutralise Afghanistan's foremost threat: spin bowling. If Rashid Khan, Mujeeb Ur Rahman and Mohammad Nabi don't have a lot of turn to work with, it seems unlikely they will take down New Zealand's Big Three, let alone successfully target that lower middle order.

And yet, New Zealand might love for Nos. 5 to 8 to have the kind of workout that would put minds at ease following the Bangladesh experience. They are yet to face the likes of Mitchell Starc, or Jasprit Bumrah and the India wristspin duo. As the tournament heats up, they, like everyone in serious contention for those semi-final spots, are all looking to move to the pointy end with as few doubts as possible.

Andrew Fidel Fernando is ESPNcricinfo's Sri Lanka correspondent. @afidelf