Haskell says Argentina are a bit of an unknown quantity
England face one of the world's most improved sides when they welcome Argentina to Twickenham on Saturday.
Argentina have changed their style from the one they used to play, which was based around set-piece dominance and kicking for territory.
They put the ball through the hands a lot more and play at a much higher tempo these days and we should be set for an exciting game on Saturday.
Pumas now red in tooth and claw
Argentina made it to the semi-finals of the 2015 World Cup but lost to Australia
Argentina now love to play with the ball in hand and have some devastating attackers.
However, they can play in the wrong areas at times.
I was lucky enough to be at their World Cup semi-final a year against Australia and although they showed at times how good they were, at times they played in the wrong areas, allowing the likes of David Pocock to turn them over.
If you are trying to run it from your own half all the time, then one mistake, one turnover, one penalty and you're conceding points.
Joining the Rugby Championship and Super Rugby has massively benefited them.
They used to have lots of players in Europe but they have loads of players based back home now and you can see how it has helped them.
Previously, when they came to World Cups (2007, when they came third, being the most glaring example) and had time to have their players together, they were a team to watch out for - much like Fiji - but away from that they struggled because of a lack of preparation time.
Now, unlike Fiji, they have that regular time together as well as regular top-level competition, and you can see how they have improved.
There are a few differences between the Rugby Championship and Super Rugby, and the sport as we play it in Europe.
The first thing is there is no relegation, so that gives teams time to develop a bit of a game-plan and not have to worry about their immediate future - you're not playing do or die rugby all the time.
I also felt from my time playing down south that the weather and pitches were better over there.
In addition, the Six Nations is a far more attritional tournament - both because of the weather and the physicality.
In my experience the Australian and Kiwi teams also don't have that same relentless physicality, although the South Africans did.
That meant each week presented a different kind of challenge for your team and you as a player.
Time to raise the roof
The Forsyth Barr Stadium in Dunedin should be a blueprint for new stadiums in the UK, says Haskell
Dunedin, which is notoriously cloudy and prone to drizzly rain (it's a bit like New Zealand's Manchester in that regard) has a great roofed-stadium.
The glass roof lets the grass grow, and it's much more simple than many roofed stadiums - it should be the blueprint for any new stadium in the UK.
My personal view is that I would rather have a glass roof on a stadium than an artificial pitch any day of the week - I'd much rather do it that way round.
I've not met a player who likes playing on artificial pitches. The boys prefer playing on grass - it's better for your joints.
Personally I think rugby should be a summer sport.
We all want to play expansive, fun rugby and when you go to certain grounds in January it's a hard thing to do because you're limited by the weather and the somewhat boggy quality of the pitch.
I look at kids running around in the mud and freezing cold and I remember that it was not fun.
Every time I run out in the pouring rain I think 'why are we doing this? Let's get a roof'.
It's difficult to encourage the next generation, and teach them about contact, when it's freezing cold and wet.
George Kruis has done very well to get back from his ankle injury only four weeks after the operation.
Yes, I know I've taken literally months to get back from a little-toe injury, but it was a slightly more complicated operation than just having a bit of bone removed from an ankle.
He has had a great recovery and I would go any faster if I could, but I'm aiming to be back for the end of December.
The Saracens lock is a very professional guy who takes a lot of pride in his game and is a very dedicated player.
He's excellent at calling line-outs and had a very good teacher in Steve Borthwick, now England's forwards coach, who he learned from at Saracens and who set his own standards in terms of attention to detail.
That's not to say other players don't also put in lots of work on line-outs - Courtney Lawes applies himself similarly in terms of dedication, but he and Kruis have a different style.
George Kruis is back in the second row for England less than a month after having an operation in his ankle
Work, eat, sleep, repeat
Kruis is a guy who's done a lot of work in the gym since he turned professional with Saracens in order to first build himself up and now maintain his 18st 5lb physique, because he was very skinny when he was younger.
He also eats like a horse - five meals a day - to maintain his target weight.
I used to be able to do that but it seems you get to an age when putting on weight, rather than trying to maintain it, becomes an issue.
After my holiday in Ibiza I carried on eating and got up to 125kg (19st 7lb), which is easily my heaviest.
However, I knew I was having five months out, and wanted to use my time as a challenge to get back into great shape - it's always good to practice what you preach. You can see how my journey has been going elsewhere on the net.
I think you have to look to the parents to see what the future holds.
My old man has always been a big guy but he's got into walking and does a ridiculous amount - he has got himself a fitness watch, and now tries to beat his score every day.
He's lost weight and his dog is now as skinny as a whippet.
Not all players stay big when they retire. I bumped into former England and Wasps blind-side Joe Worsley and although he's still got those massive hamstrings, his upper body has shrunk, without the constant weights and training.
Another big guy, former Wales number eight Ryan Jones, has been doing iron man triathlons and has lost literally three stone.
Safe to say you'll never catch me doing an iron man when I retire - the odd sprint triathlon perhaps.
I can't lose too much bulk when I retire because I've got quite a big head (literally and metaphorically, some might say) and I'd look like a toffee apple on a stick.
I'll keep on doing some training though, a bit of aesthetic stuff. Nothing wrong with a sprinkle of vanity.
Has the era of the specialist now passed?
Elliot Daly did very well on the wing last weekend and it's good to see my Wasps team-mate get another run.
He is normally a centre but has great pace and finishing ability, which you need in a wing, but his all-round ability - such as his kicking - means he offers other options too.
The key to a winning team is getting the right balance throughout the side for the game-plan you want to play, and these days the number on your back means very little.
That means, for instance, you don't have to play a specialist winger or open-side flanker, provided you have the finishing ability or ability to win turnovers scattered throughout your team.
The game is changing constantly and, as players get bigger and stronger, so you need to have players who are multi-skilled.
Most sides are evenly matched in physical and fitness areas these days, so it then comes down to game-plan and individual points of difference being key.
'Test rugby is a hard game'
The best teams are all about winning, as the All Blacks proved last weekend. They understand what they do well and have the ability to adjust under pressure.
After New Zealand lost to Ireland in Chicago they went away and adapted, and a hurt All Blacks side is a dangerous All Blacks side.
On Saturday they came out and went after Ireland with their physicality, which is a sign of a world class team.
Test rugby is a hard game. As players we think a lot of the time that people are going over the top worrying and panicking about stuff, and when I saw the Sam Cane tackle on Robbie Henshaw it looked to me like Cane hit him as he spun - it happens.
The best teams in the world are the most physical and as long as players aren't deliberately trying to hurt players, it is what it is.
Gouging, biting and deliberate high tackles are all wrong, but hitting someone at shoulder or chest height and sliding up is something that happens - it's a contact sport.
All Blacks flanker Sam Cane was cited for this challenge on Robbie Henshaw but cleared by a disciplinary channel
All we want as players is consistency in the way games are refereed.
Joe Launchbury is not the kind of guy to try to hurt somebody but, although he was off balance, he caught Asaeli Tikoirotuma as he tried to kick the ball through last weekend and rules are rules, he now has to serve a two-week ban.
However, when the same thing happened and he got booted in the head in the Premiership semi-final last year against Exeter nothing happened.
That is the sort of thing that frustrates players and needs to be improved.
Don't become a casualty
I think of all of England's autumn Tests this is the hardest one to call because Argentina are a bit of an unknown quantity.
England will be worrying solely about themselves and will be looking to impose themselves on the Pumas.
Expect to see England's big forward carriers running off Ben Youngs and for the scrum-half to be sniping as he did against South Africa. It will be high-pace, high intensity, high physicality.
England will be disappointed about a couple of tries they conceded last weekend against Fiji and even though they won by 50 points it was interesting to hear the players talking about improvements.
It's not long ago that we beat Fiji by a narrow margin in the World Cup - now we put 50 on them, and there is no satisfaction.
It's a case of keep improving, keep pushing, never become casual, or you become a casualty.
James Haskell was speaking to BBC Sport's James Standley.
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