What makes Flintoff great?

There's been much debate over whether Andrew Flintoff can be called a great player. He may not have statistics or longevity on his side but Simon Barnes feels it is perfectly possible to achieve greatness without either and points to Bob Beamon, Roger Bannister, Jesse Owens and Mark Spitz who achieved greatness through a flash, an hour or a week of magic. He writes in the Times:

Flintoff was great for a couple of months. In those two months, in the summer of 2005, England beat an Australia side packed full of indisputably great players, regaining the Ashes after 16 years. Flintoff was the inspiration, the deal-breaker, the match-winner and the series-winner. In this brief, enchanted period he was genuinely great, and if the rest of his career has failed to measure up, then it was much the same with Beamon.