They might be a developing side, but few will tolerate that excuse if they miss qualifying for the 2019 World Cup in Zimbabwe during March. The hosts, Afghanistan, Ireland and others are expected to give them a thorough examination.
Coach Stuart Law acknowledged their flaccid showing.
"It was a pretty disappointing tour. New Zealand played good, disciplined cricket, but we fell short.
"We need to do a lot of hard work, planning and understanding. That means some soul-searching by looking in the mirror and asking if we gave it everything to change a game, get into a game and win a game.
"It's not just going to happen."
Law said that was made worse by the unavailability of several players who helped the West Indies win the World T20 in 2016.
"They know this format inside out. It's difficult trying to organise players when they pull out at the last minute. It's almost impossible trying to sort visas and flights from the Caribbean in 24 hours.
"Those decisions didn't help, but the players we had were good enough to play with passion and pride to show we can play the game.
"Sometimes you have to go to the bottom before you move forward. Everyone's feeling down."
Talisman Chris Gayle personified the West Indies' under-performance.
He arrived in New Zealand after pummeling 146 off 69 balls to help Rangpur Riders win the final of the Bangladesh Premier League over the Dhaka Dynamites.
Gayle scored 38 runs from 47 balls across four innings and looked vulnerable against short-pitched bowling.
"Write him off at your peril," Law said.
"He didn't click in this series. He had a viral infection in the one-dayers and, while T20 is probably his best format, he didn't get the starts he wanted.
"He's played this game long enough. He knows how to do it. He was pretty good in England a few months ago."
Law insisted the 38-year-old has more to offer.
"Right now it probably doesn't look like it, but there's plenty of cricket left in the big man. He can destroy any attack, it doesn't have to be a minnow.
"He's central to the way this dressing room ticks, and commands a lot of respect. He's just got to start performing in the middle again."
Colin Munro was again central to New Zealand's fortunes, this time with the Black Caps' fastest T20 century off 47 balls.
He put his time last season with the Caribbean Premier League's Tribago Knight Riders to good use, and received a standing ovation for his feat.
"I had played every one of those players; I knew what they'd try to do and where they'd bowl.
"Take Sammy [leg spinner Badree]. He's played in leagues around the world and I've got out to him playing back.
"In Nelson [for the first T20] that nearly happened a couple of times, so I kept telling myself to get forward."
Munro shared a stand of 136 in 11.3 overs with Martin Guptill, the Black Caps' eighth century partnership for the first T20 wicket and their second highest in the format.
The pitch had enough pace to bring the ball on, but the bats of Munro (104 from 53 balls) and Guptill (63 from 38) welcomed the confrontation.
Their effort contributed to 243 for five, a record New Zealand T20 total, overtaking the 214 for six set against Australia in February 2010 at Christchurch.
Munro became the first player to score three T20 international centuries, overtaking the braces from Brendon McCullum, the West Indies' Evin Lewis and Gayle, and India's Rohit Sharma.
Munro only started opening the batting for New Zealand after working with McCullum in the CPL. He paid tribute to the former New Zealand captain.
"I'll keep using Baz as a mentor. I texted him after the Bash Brothers [McCullum and Chris Lynn] were a good watch last night [in their victory over the Melbourne Stars in Australia's Big Bash League].
"He tells me the same things. Stand still, be aggressive and have some fun."
