I used to believe coach Gregg Popovich was just monitoring Tim Duncan's minutes to keep him fresh for the playoffs. For a while I believed Duncan did less so that Manu Ginobili and Tony Parker could shine more. Everyone could see Shaquille O'Neal falling to pieces, but Duncan's decline was always masked by his steady presence and the wins.

I used to be blind, but thanks to the Memphis Grizzlies, now I see.

Tim Duncan's at his most demonstrative after calls with which he disagrees. Ronald Martinez/Getty Images

Tim Duncan is old er.

I'm hedging just a bit out of respect, which Duncan has never had a problem getting.

It's the love that's been on back order.

He is arguably the greatest power forward to ever play, and yet when he was in the NBA Finals, we didn't bother to watch (two of the all-time lows for Finals TV ratings featured him).

He's been an All-Star starter but never the top vote getter.

In 2003, Duncan was not only an All-Star, but repeated as league MVP, and was MVP of the Finals while leading the San Antonio Spurs to their second NBA championship (he was also instrumental in the franchise's first in 1999) and yet his jersey sales didn't crack the top 10. Although he was by far the best player in the league that season, fans bought more gear bearing the names of Jalen Rose and Lamar Odom, two players who have never even been named All-Stars.

See what I mean? Respect. But no love.

Regardless of what happens in this series with Memphis, it is clear the window's closing for these Spurs. If my hunch is right, when Duncan's contract expires in summer 2012, he will not re-sign. He will retire.

And if this is indeed the case, I hope the fans -- so obsessed with crossover dribbles and dunks -- give an overdue standing ovation to a player whose signature moves are winning and avoiding the curtain call.

Why would he retire?

In short, dude is tired.

Tim Duncan, left, and David Robinson won two titles together. Nathaniel S. Butler/NBAE/Getty Images

Four years at Wake Forest. Thirteen seasons in the league. The equivalent of two full regular seasons in the playoffs (175 games and counting). Plus, he just turned 35, so recovery takes a little bit longer.

Duncan never had great lift, but now his feet have taken root in the ground; rebounds out of his area are now rebounds out of his reach.

And after two MVPs and four championships, there really isn't a reason to come back even slower and achier just to get bullied by a Zach Randolph, posterized by a Blake Griffin or -- if the Lakers find a way to snatch Dwight Howard from Orlando the way they got Shaq in 1996 -- abused by D12.

No, Duncan deserves better than that.

But that's not the only reason why he'll leave. Unlike, say, a hobbling Seattle SuperSonics version of Patrick Ewing or the injury-prone Lakers version of Karl Malone, Duncan doesn't need to stick around and chase a ring to validate his career. And unlike Shaq or Michael Jordan, he doesn't need the attention.

In fact, part of the reason why we don't love Duncan is because he doesn't go out of his way to get us to notice him. Critics say he has no personality but, the thing is, he does. He just doesn't bother to show it to us. He graciously accepts the fame that comes with being a 13-time All-Star, he just doesn't flaunt it. As a result, we've become indifferent to a man who really should have been the face of the league: never in trouble, philanthropist and humanitarian off the court, the game's biggest winner on it. But because we've become a culture conditioned to reality TV and manufactured celebrity -- paying attention only to big personalities or vacuous people who are famous for making a spectacle of themselves -- we don't fully appreciate the beauty of someone who focuses his public persona on being an elite athlete, a person like Duncan.

I'm not an irrational fanboy who thinks he's perfect, or anything like that. He does complain to officials a lot, eyes wide in disbelief, more demonstrative than just about any time off the court. And that whole thing with never playing international ball again because of FIBA rules after the 2004 Olympics rubbed me the wrong way. But I do recognize that Duncan is quiet and talented in an age in which we prefer our gods to be loud and mediocre. Which only partially explains why in 2006, Stephon Marbury, who up to that point had never won a playoff series, had the league's fifth-most popular jersey and Duncan, who had just led the Spurs to a third championship the year before, was out of the top 10, again.

Tim Duncan had gradually spent less time on the court. When his contract expires, will he step away from the NBA? Jed Jacobsohn/Getty Images

After one final season, Duncan will retire because there's nothing more for him to do. He's earned close to $200 million in NBA salary alone, so money won't be an issue. And unlike David Robinson, who stuck around until he was 37 because he loved the game and felt Duncan could do the heavy lifting en route to one more ring, Duncan isn't seeing much relief on the bench. Barring a trade, he's looking at Dajuan Blair as his workhorse successor. And while Blair makes for a good story, Duncan knows the Spurs are going to need more than a good story to win another ring.

If he misses the guys, he can come back to visit. There's no need to take elbows for 82 games just to say "hi."

Of course, the locals have always known what they have. Last week it was reported the Spurs led the league in regional TV ratings this year. You can bet that when the Big Fundamental walks away, the royal wedding will look like a Texas high school prom compared to what San Antonio will do to honor him.

But what about the rest of us? Next season may very well be Duncan's last. Will we come out of our misguided "SportsCenter"-highlight fog long enough to properly shower him with the love that rightfully belonged to him for a decade, or will we be too busy talking about another Griffin dunk? No knock on the rook, it's just that when Duncan came into the league in the 1997-98 season, he averaged 20 points and 9 rebounds -- in the playoffs.

The next year, the Spurs won the whole thing.

Huh, no wonder Duncan is looking so old. Whether we love him or not, he's owned the league for a long time.

LZ Granderson is a senior writer for ESPN.com. He can be reached at lzgranderson@yahoo.com.

MORE COMMENTARY »