Sad day for a Spurs fan, but it's due. He just couldn't bring it anymore, and father time remains undefeated.
People always have this notion that Duncan's peak was inferior to the other greats like Shaq or Hakeem, and I used to thought that as well because of the raw numbers, but when you really look into the details, Duncan was eye to eye with them when measuring peaks.
It's sort of accepted truth that Jordan, Lebron, Hakeem, Shaq, Bird, Wilt and Jabbar have peaks that are untouchable by others, but Duncan, when you actually look at the numbers in details, actually measures up, he wasn't that far off. Jabbar, Jordan and Lebron kept those numbers over a longer period of time than anyone else did though.