The ageless Tim Duncan has finally aged

We need to acknowledge that Tim Duncan might have played his last game in San Antonio. The Spurs face elimination in their series with the Thunder, and Oklahoma City can clinch at home on Thursday. The Spurs could absolutely win that game to bring the series to a Game 7 back in San Antonio, and Duncan may decide to keep playing beyond this season in either case. But considering the spectacular, historic career the Big Fundamental has had, we should acknowledge every moment could be his last in the NBA. We owe him that, at least.

There is no farewell tour. There are no slick video montages. No rapper will be sitting courtside wearing a sweatshirt adorned with Duncan's name and the date and the phrase "St. Dunstan's Episcopal's Finest." If Thursday indeed marks Duncan's final NBA game, or if it's Sunday or next month or even next year, no one will know until after the fact when the greatest power forward of all time and one of the five greatest basketball players in history just simply isn't there. When it happens -- whenever that is -- the sports world won't stop to bask in his afterglow.

Part of it is that Duncan's potential farewell isn't the most important thing happening to his team. The Spurs, after all, are fighting for a championship. The other living legend who said goodbye this year, Kobe Bryant, played for a team at the bottom of the standings. There was little to do but appreciate his legacy. San Antonio has other matters on its mind right now.

But that's just part of the reason that Duncan's possible exit has generated so little public emotion and longing from the basketball world. Kobe was all bombast, ego, spotlight excellence and brashness. Duncan is not. Big men will never get the attention guards and wings receive, and while Kobe was the quintessential marquee guard, Duncan is the perfect embodiment of what an NBA big man should be.

Or at least he was. It's over now.

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Duncan is 40, and looks it. Those summer wind sprints under the Texas sun can only do so much. Duncan's career could have ended six years ago, back when his creaky knees hurt his ability to maintain his conditioning. By 2010 he was clearly on the downside of his career; no longer a 20-point scorer and no longer able to be the best player on a championship team. The season before the lockout, 2010-11, saw Duncan play just 28 minutes per game and ring up the lowest per-game stats of his career. The Spurs were still great, winning 61 games. But the Grizzlies shocked them in the first round as Duncan had a poor showing.

The lockout may have saved Duncan's career. Stories about Duncan working out with Danny Green and other young Spurs during the otherwise unwelcome break made the rounds. With Kawhi Leonard infusing the Spurs with a sense of possible future glory, Duncan bounced back strong, getting more production on the same low number of minutes. San Antonio in 2012 finished with the best record in the league, winning 50 games despite playing just 66. They went all the way to the West finals, where the rising Thunder won four straight to earn their first and only Finals berth.

Duncan was better still again in 2013, boosting his production (just about 18-10) and minutes for a team that came within a rebound of winning the championship. Leonard had blossomed, and Gregg Popovich had remade the team to emphasize passing and movement. The next season with vengeance on their minds, Duncan missed the All-Star Game for the first time in his career, but the Kawhi- and Tim-fueled Spurs stomped the Heat in a Finals rematch for Duncan's fifth title. He made a final All-Star Game in 2014-15, but the Spurs ran into a buzzsaw Clippers team in the first round despite Duncan playing great as a 39-year-old in that series (18 and 11 on nearly 60 percent shooting).

Duncan's scoring numbers fell off a cliff this season. He struggles to get open looks consistently and defers heavily to Leonard, Tony Parker and others. He's averaging fewer than five points per game this postseason. On offense, LaMarcus Aldridge has made Duncan nearly irrelevant. Duncan's own age has made him less effective on the boards (one defensive rebound in 10 chances on Tuesday, per NBA.com) and, to a certain extent, defense. The mind is there, but the body is not. He's no longer quick off of his feet and his lateral movement is slowing.

Yet because his brain is so full of basketball knowledge, because brilliance doesn't fade like fast-twitch muscle, he can still anticipate attackers and make spectacular plays ... like his fourth quarter block on Russell Westbrook.

Duncan hit the bench for a breather after that play. Steven Adams, the man he'd been guarding to that point, got a dunk on the ensuing possession.

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In my personal basketball history textbook, Duncan goes down as the best power forward of all time, the second-best big man ever and the third-best player in history. The only big man in history who exceeds Duncan's two-way impact is Kareem Abdul-Jabbar, who made 10 All-Defense teams and won two scoring titles. (Kareem also won six titles, six MVPs and had an incredibly long career.) I've debated Kareem vs. Duncan with myself frequently since the Spurs won No. 5 two years ago. At this point, Big Fun doesn't quite beat Cap. And no one beats Jordan. So Duncan is No. 3, for now. LeBron is coming.

Tim Duncan is the greatest player of his generation, and it's not particularly close. This might be the end, and there is little fanfare and no parade. Part of me thinks Duncan, the most quiet and spotlight-allergic superstar in the league, is content with that. If he wanted a grand farewell tour, he would tell the Spurs and they would get it done. Kobe wanted it, and a basketball world that rightfully fawned over him for two decades obliged. Duncan prefers it this way, no doubt. How appropriate for Duncan to go out not in a spectacle of media crush and celebrities, but in a hard-fought playoff series. It says everything about his career and his legacy.

If this is in fact the end, of course. We've been made fools for writing off Duncan's career in the past. While all signs point to Tim being done, can we ever really be sure?

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