I think your hypothesis makes a lot of sense. If you think about it in order out perform the market over the last 15 years all you had to do was two things right.
Back in 1999 you had to be careful not sell bonds,cash etc, and buy stocks. Which sound simple in retrospect but of course during 1999 everybody knew that stocks were going to the money cause the internet changed everything.
Then in late 2008/2009 you simply had to avoid selling all of your stocks.
Actually you didn't even have to know anything about the market, all you had to do was realize that Warren Buffett knew more than you about investing and listen to him.
In 1999, he told people stocks were too expensive and 2008 he said to buy stocks.