Williamson's workload, Santner's spot - five questions for New Zealand

Their 3-0 loss to Australia was a harsh reality check to a Test side that had done very well in 2019

New Zealand have been handed a brutal 3-0 drubbing in Australia after arriving with hope of competing strongly - and perhaps even winning a series here for just the second time - amid loss of form for key players, injury and illness. They will now return home for the rest of their summer and a visit by India with plenty of questions hanging over them
Captain's workload
This can go down as the toughest tour of Kane Williamson's career. Even before he was laid low by the flu in Sydney it had been a forgettable trip with a poor return with the bat and some questionable tactics. If the second-innings lbw in Melbourne was unfortunate, then the first-innings swipe at James Pattinson was a shot completely out of character.
There is a huge amount on Williamson's plate as captain across all formats. New Zealand Cricket have started to acknowledge the need to be careful with their captain, resting him from occasional T20Is, but it may need a more serious look at his demands. It's easy to say that he should not play in the IPL, but NZC do not have the funds to protect their best players as the richer boards can do and they have had to take a pragmatic approach to allow them to play in India. One lean series with the bat does not mean it is panic stations - who knows how he would have done if fit for Sydney - but New Zealand need Williamson at the top of his game when they take on India next month.
Coaching still Stead(y)?
The transition from Mike Hesson to Gary Stead had been successful until arriving in Australia with a Test series win against Pakistan in the UAE, a drawn series in Sri Lanka, home wins against Sri Lanka, England and Bangladesh topped with a World Cup final. Like the squad as a whole he has been dealt a tough hand on this tour and there was probably a limited amount he could do, but a few selections (arguably giving Jeet Raval and Mitchell Santner a Test too many then leaving out Tim Southee) has raised questions, plus the way the team prepared for the series - although that can't lie entirely at his door. He is only contracted until the end of the T20 World Cup in October so will want a good end to the home season after the travails in Australia.
What's the best spin option?
It was always going to be an area where New Zealand would struggle to compete, but their spin resources were shown up badly on the tour in conditions where Nathan Lyon had a major say. Santner took just one wicket in the first two Tests before illness ruled him out in Sydney with Todd Astle and Will Somerville coming into the side. That pair did their best, and Astle produced some impressive spells, capped off by the fine googly that removed Joe Burns in the second innings, but they remained a long way short of having a significant impact. It came after a 2019 where spin had a major say in New Zealand's overseas successes in the UAE and Sri Lanka with Somerville and left-armer Ajaz Patel both playing key roles in victories. Santner may remain first choice for the visit of India, but Astle could have put pressure on him.
Batting order
Tom Blundell's century was a rare high point for New Zealand (along with the indefatigable Neil Wagner) when he was parachuted into opening at the MCG and responded with a second-innings century. It is now all-but-certain that he will get a run as Tom Latham's opening partner with Raval, who battled bravely in Sydney after also being struck by illness, dropping out of the squad and Glenn Phillips set to become the reserve batting option after his promising debut. Henry Nicholls has credit in the bank, but could need a good series against India to secure his spot having not scored a fifty in his last nine innings.
Succession planning
There was a sobering view from Ian Smith, the former New Zealand wicketkeeper, before this series when asked if they had the depth to replenish the side when this generation starts to retire. His short answer was 'no' and while there is unlikely to be any mass retirements in the near future, New Zealand must keep an eye on what is behind the current pack. Ross Taylor will likely be the first to leave while Wagner is nearly 34 although benefits from only playing Tests and looks like he could go on and on. Phillips' emergence is encouraging while Kyle Jamieson, a tall pace bowler, was called into the squad and Lockie Ferguson, who he replaced, should have a big part in New Zealand's future. The situation around Tim Southee will be interesting to watch after he was left out in Sydney. He, along with Latham, would be options to take some of the captaincy burden off Williamson in the limited-overs formats if a change is considered.

Andrew McGlashan is a deputy editor at ESPNcricinfo