Alastair Cook is now sixth all time on the test run scoring list.

ANALYSIS: When contemplating Alastair Cook's exceptional record playing for England, it makes you wonder about New Zealand's best batsmen.

What if, is the question going through the mind.

Cook, the former England captain, is slowly, and let's emphasise, slowly, working his way through the record books.

GETTY IMAGES Alastair Cook of England celebrates making his double century, against Australia during the Ashes.

He's now the sixth highest run scorer in test cricket history, scoring 11995 runs in 152 matches and counting.

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Here's where the thinking on Cook gets a little cloudy.

GETTY IMAGES Ross Taylor has played just over half the matches of Alastair Cook. How does he really compare?

Over 274 innings at bat, he averages 46.49.

Only 13 men have crossed the 10,000 run mark in test cricket, and just two of those average under 50. Mahela Jayawardene averaged 49.84 in his career with Sri Lanka, and then there is Cook.

While his batting average is considerably lower than his peers, it's important to note that Cook is an opening batsman, and Sunil Gavaskar (10122 at 51.12) is the only other opener in the 10,000 club. He takes the shine off the new ball against the freshest bowlers. It's no small task.

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There is no denying his class, then. What you have to wonder, though, is what others could have achieved with the same opportunities as the England man has had.

In a career spanning 12 years, Cook is currently playing in his 152nd test match. By the end of the week, he will have batted 275 times in tests, which means he gets nearly 23 opportunities each year to do his thing at test level.

Let's compare that to Ross Taylor.

Taylor debuted for New Zealand in 2007, a year and a half later than Cook. Where Cook has played 152 matches and batted 274 times, Taylor has played in just 83 matches while batting 149 times.

If, a year and a half from now, Taylor matched Cook's record for matches played, and innings batted, he would have 12,260 runs.

Would Taylor be seen as an all-time great in those circumstances? Is he for his current figures, 6246 runs, at 48.04?

PHOTOSPORT If New Zealand played as much as England, Tim Southee would be nearing the 400 wicket mark.

The same question could be asked of bowlers.

Stuart Broad made his test debut a month before Tim Southee did. He sits on 398 test wickets at an average of 29.10, and could should go past the 400 mark in the next day or two.

At Tim Southee's current clip, he'd be on 378 wickets at the same point as Broad, also eyeing the 400 mark.

GETTY IMAGES England batsman Joe Root looks likely to surpass 10,000 test runs in future.

Opportunity is the key for these players, and New Zealand simply don't get the opportunities to go down as true greats of the game.

We're going to see more of it in future, too.

Joe Root made his England debut two years after Kane Williamson, and yet he has now played in more test matches than his New Zealand counterpart.

Should the two players continue playing test matches at the same rate, and at their current average, Root will end with 13,552 runs in test cricket, while Williamson would end with 10,883.

That would suggest Root is much the better batsman, but by nearly 3000 test runs?

Those would both be incredible figures, but if Williamson played matches at the same rate as Root, he'd be on 12,908.

DAVE ROWLAND/GETTY IMAGES Kane Williamson will end up as New Zealand's best ever batsman if he keeps up his current standards.

Given time, who knows which way their averages would go.

Form comes and goes and class can fade, but regardless of their talent, the Black Caps will never be among that top echelon until they get the opportunities of their rivals