The 2008 cut off is also due to age rather than IPL. Of course guys who are 28-32 years old are far more likely to be the best in the world than a 25 or 35 year old.
Your year chosen is also very, very tenuous - they can't have played more than a couple of games before 2008 and to do so as teenagers already points to them being generational talents rather than solid batsmen like Tom Latham. I will also add an NZ specific rebuttal - KW was created in a far weaker FC system than the one of Tom Latham or even more recently an up and comer like Ravindra.
The biggest difference between the outlier of the batting boom 00s and today is pitch de-homogenisation.
Look at a team we both know well Steve. In 2004 and especially 2010 NZ sides who would be pulverized by Kane's side stood up to Indian sides in India despite those Indian sides on paper being far better. On the most recent tour, NZ found it a lot tougher to match a side their equal.
The biggest difference for the NZ sides was the Mumbai deck in particular compared to the worldwide average pitch of 2004 and 2010 and a lack of practice games. Pitches worldwide in the 00s had more in common with each other than those of today.
We've returned to the historical norm of pitch variety and it has been a savage adjustment.
I don't think blaming the IPL is looking deep enough.
That's cool, I don't agree with a lot you said but mine is a perspective and so is yours. Didn't stop Smith, Williamson, Root, Kohli etc averaging 50+ in their 20s did it? In history there's been plenty of >28 year olds who have averaged 45+.
My year of 2008 isn't tenuous at all. It's a clear marker in terms of when the game became lucrative. You know that as an NZ fan, it was around the time that Brendon started to have reservations about whether he would continue to be an NZ player, turning up late to overseas tours, even those Champions League T20 tournaments became a major focus. Remember how much our domestic sides used to value our T20 comp?
It's not about debuting in 2008. It's about the fact they had built their games at age group and initially in senior cricket in longer form cricket before this time. They weren't building their games with any knowledge or idealism of being a short form gun for hire. And I'm also not talking about the quality of the FC comp. I'm talking about the way guys set up their games. Kane Williamson always wanted to bat time. He left balls. He knew where his off stump was. He played straight. That's not the modus operandi of junior players now.
I don't agree with those Indian examples, either. That 2004 side was a very, very good side and especially playing spin. Fleming was a genius on the sub-continent. Richardson worked feverishly on his game. Those teams prepared well - and what's more, they had time and space to prepare well. I think you're vastly overstating the pitch issue. Maybe it's a part of it, but if you consider (like me and others) that techniques are considerably compromised in the modern game, any chance in the quality of pitches would be exposed.
Again, I am not 'blaming' the IPL. The IPL is great for a lot of people. I'm talking about T20 and the ability to make money the world over. I've seen those graphs that show downward trends from 2008. How is that co-incidence? Even if you believe generational bowler quality is a factor and pitches as well, surely there'd be no one debating me that T20 focus has the real potential to erode techniques?