Coach Mike Hesson says it's an issue they're grappling with: "I thought we played Swann okay in those first couple of games; the wickets didn't turn a heck of a lot and we maneuvered him nicely.
"Tredwell bowled well at Notts. They're good spinners but not unorthodox like those of the West Indies and Pakistan who we have traditionally struggled against.
"The wickets are not as good [for batting] as we thought at this time of year. The ball hasn't swung but has certainly spun and stopped on the wicket a bit."
Hesson says it has changed their own bowling mindset at the tournament.
"It was the first time New Zealand has used 30 overs of spin in our ODI history when we played Australia. Our spinners have been outstanding: Kane's grown another leg, we know what Dan [Vettori] can do and Nathan [McCullum] was vying for Dan's spot at the start of the tournament so [to still be in the side] it's a nice position for him to be in."
There had been no dramatic deterioration in Vettori's fitness since the abandoned Australia match. Hesson expects his veteran bowler to play England.
The New Zealand experience reflects a wider trend over the course of the tournament. Runs have had to be earned.
Purpose-built cricket grounds, slower pitches and delivery variations have seen spin bowlers strike back. Gone is the trend where ODI cricket tended to be glorified tee-ball.
Out of 15 completed innings ahead of the South Africa/West Indies match, batsmen dominated in just six. In the first match, where India beat South Africa at Cardiff, both sides made over 300.
Two more bat-dominant matches occurred when Sri Lanka chased down England's 293 for seven at the Oval and England eased to 269 for six batting first against Australia at Edgbaston. India cruised to an eight-wicket win chasing 234 with 10.5 overs to spare, also at the Oval.
Two of the seven matches played at the time of writing have seen chases of less than 175 narrowly achieved (including New Zealand against Sri Lanka).
Slow bowling has become a weapon (an unusual statement in England during June, given the prevalence for green tops). Thirty-five of the 117 wickets (30 per cent) in the first matches of the tournament came in that fashion.
The cricket-specific grounds of the Oval in London, Edgbaston in Birmingham and Swalec Stadium in Cardiff refuse batsmen the bail-out option of miscuing a slower bowler into the stands - as can and does happen at a small ground like Eden Park.
Sweepers are instead stationed expectantly inside the rope and scoring rates come down. There have been fewer than six sixes per match so far.
"There's not much of a short side at any of the venues," Hesson says. "Cardiff is short straight but you can protect that [by holding the ball back] on a slower wicket. The risk/reward factor is more in a bowler's favour which is no bad thing. You've got to get all of it to clear the ropes."
"There's not much of a short side at any of the venues," Hesson says. "Cardiff is short straight but you can protect that [by holding the ball back] on a slower wicket. The risk/reward factor is more in a bowler's favour which is no bad thing. You've got to get all of it to clear the ropes."
Limited sun in the English summer has played a part. The pitches have not been baked hard and the wickets are struggling for bounce and carry. Players are forcing the pace of the ball in front of square. It is presenting catches to in-fielders and misjudgments of pace which lead to lbws.