New Zealand v England: Tourists cannot rest on their laurels in Test series

The fitness of Mark Wood (left) is one of several issues that England have to address in New Zealand

The first part of England's mammoth winter went badly. Now, the Test series in New Zealand will say an awful lot about how the past six months will be viewed.

After the 4-0 Ashes defeat in Australia, everybody - the supporters, players, coaching staff - has to regain focus, especially those who have been on tour for months.

There is some trouble brewing if this series does not go well for England, and it is going to be a difficult one. It is essential, on a number of fronts, that they win this two-Test series.

New Zealand will not be pushovers. The first Test in Auckland, which starts at 01:00 GMT on Thursday, is a day-night match and the ball will hoop around and make batting difficult.

It is not going to be an easy trip by any means.

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England have a bagful of points to prove

Apart from Jonny Bairstow, who has had an excellent winter, and James Anderson, comfortably England's best bowler during the Ashes, you can point fingers at virtually everyone, and that includes the coaching staff.

No-one can really rest on their laurels after the winter. All the batsmen have questions to answer and, without any doubt, this is the last chance for some.

Mark Stoneman and James Vince know they have to perform. In a way, that focuses the mind - it is a good challenge to have.

Vince, in particular, has been fortunate to play the 12 Tests he has. He knows he is on borrowed time. Stoneman has not nailed down that opening position but two decent matches here could easily turn things around.

After all, England are pretty desperate for players. They are crying out for a number three and they have accepted now that Joe Root, who is the best number three in the team, does not want to bat there.

Do they leave Vince there? Do they move Dawid Malan, who averaged 42.55 batting at five against Australia, up the order? Is the uncapped Liam Livingstone going to play? There are issues that need to be resolved, and be resolved quickly.

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As for Alastair Cook, there are always questions about him. He had a very mixed 2017 and now has to produce. You feel he is safe at the moment, because he is still capable of big hundreds, but he has not been consistent.

England have to listen to Geoffrey Boycott - get in and stay in.

There were question marks over Stuart Broad's longevity during the Ashes, and he did not take the new ball in England's two warm-up matches last week.

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Does that mean Chris Woakes partners Anderson first up? Or can Mark Wood take that role - and maintain his fitness?

Moeen Ali, too, has got to turn his winter around. The off-spinning all-rounder took only five wickets in the Ashes at an average of 115 and, in more English-type bowling conditions in New Zealand, he will need to back up the seam attack.

Simply having Ben Stokes back is a big step in the right direction for England, although there is a question mark about his fitness, bowling-wise. But his presence alone will lift the team.

Why this series is so important for Root

This series is a big challenge for Root as captain. I am interested to see how he performs after the 4-0 Ashes loss.

You hope, from his point of view, his team play well. He will not have enjoyed the Ashes series one bit, and I hope he has not lost confidence in himself.

If it does not go according to plan in New Zealand, you imagine Root's confidence as captain is not going to be very high, and the real worry is that would rub off on his batting.

Root will want to score more runs than he did in the Ashes, where his highest score was 83 in five Tests, but that is something that runs all the way down the order.

Head coach Trevor Bayliss' away record in Test cricket is pretty poor - England have lost nine and drawn two of their past 11 away Tests - and he has hinted he wants to split the job up.

I am not sure that is going to happen, although in 2019 England have a World Cup and Ashes to prepare for at home, which is too much for anybody.

New Zealand - tougher than they look

England's last-wicket pair of Monty Panesar and Matt Prior held on to secure a 1-1 series draw in Auckland in 2013

The most recent Test England played in New Zealand was in Auckland five years ago. It was a great match - and one New Zealand really should have won.

Matt Prior made a rearguard hundred and last man Monty Panesar batted heroically as England kept the hosts out in that final half-hour and secured a draw.

Now, New Zealand are a much tougher team than they look and, under lights, with a pink ball, they will be a handful.

Trent Boult and Tim Southee get the ball to move, while Neil Wagner had tremendous success against West Indies, taking 7-39 in Wellington to set up a 2-0 series win.

They have world-class batsmen too, in the form of captain Kane Williamson and Ross Taylor.

They will not be easy to beat - and they know they have a great chance of getting one over on England.

Jonathan Agnew was speaking to BBC Sport's Amy Lofthouse.