Manu Ginobili: "[Pop] makes your role very clear at every point." Tim Duncan: "He defines everybody's role, he sticks them right in the slot, and then you have to fight your way out of that role." -- Excerpt from Champions Revealed

Lately, we've seen Jonathon Simmons take over the backup small-forward spot more often than not, effectively sopping up Kyle Anderson's rotation minutes, though both are still playing a healthy amount thanks to all the blowouts the Spurs find themselves involved in. In the big scheme of things it's not that big of a deal --we're talking about the 10th man, here-- but it still represents a bit of an upset considering the respective pedigrees of the two players involved.

The Spurs invested a first-round pick in Anderson, albeit the 30th one, and he's only 22 and it's his second year in the program. Simmons, on the other hand, is a 26-year old undrafted free agent with zero professional experience outside of the D-League.

As you know, PATFO were impressed enough by Simmons' work in the Las Vegas Summer League to sign him to a two-year contract, but he was still considered an end-of-the-bench type and a long shot to be a contributor, and a fair bet to still spend the most of the year in Austin. He indeed started the campaign there, not doing himself any favors with a tentative showing during the preseason, where he often looked lost and overwhelmed on the floor. By contrast Anderson was expected to hold down a rotation spot, with his only competition there coming from veteran Rasual Butler. So, what changed?

Take a look at these plays.

This is Simmons sinking a three pointer from the corner on Dec. 9 at Toronto. Here he is is at Atlanta, on Dec. 12. And again Dec. 21, vs. Indiana.

Now look at this play.

"How do you call that one? Everybody touches it!" - @seanelliott_32 pic.twitter.com/vkbkthSdx3 — San Antonio Spurs (@spurs) December 24, 2015

Did you spot the problem?

On the surface, it looks like another textbook example of the Spurs' "Beautiful Game" passing clinic. But watch it again. Anderson clearly passes up a corner three, the most efficient shot in all of basketball. He was supposed to shoot that shot. He over-complicated the play. That it wound up being salvaged by the brilliance of Manu Ginobili misses the point. It's about the process, not the result.

As it happens, Anderson actually played quite well at Minnesota. He sank 5-of-6 shots, tied his season-high with 10 points, and added five rebounds and three assists. The play in question came in the third quarter, and Anderson had already deposited some solid play in the first half in Gregg Popovich's memory bank. Plus, the Spurs did wind up scoring on the play and were already up a million points in the game.

However, that sequence exemplifies exactly the kind of play in which Anderson has been benched by Pop a handful of times -- often just after entering games late in the first or early in the second quarter -- along with another handful where he was yanked for miscues on defense. For example, when the Timberwolves visited the Spurs less than a week later, Anderson lost Chase Budinger for a backdoor layup seconds after they both subbed in to the game. Popovich immediately pulled him on the next dead ball and both he and veteran players addressed Anderson on the bench.

It's plain that Anderson has markedly improved between year one and two. He's in better shape, he seems to understand the offense better and his shot is more refined. I don't question his work ethic. But when it comes to the games, he just defers too much and isn't aggressive enough. Minutes go by with him on the floor where he doesn't dent the score sheet with a shot attempt or an assist.

Look at the team's usage stats, per NBA.com. Simmons ranks sixth. Anderson is a couple notches ahead of Butler for dead last. Matt Bonner uses a higher percentage of possessions than Anderson. And lest you think that usage is all about who can indiscriminately chuck up the most shots, let's look at assist percentage. We think of Patty Mills --affectionately-- as a chucker, but see for yourself what his assist percentage is and compare it to Anderson's. Passing was supposed to be Anderson's forte, but only 11.8 percent of his possessions end in assists compared to Simmons' 17.6. Anderson's passing moves the ball along the chain. It's not really accomplishing anything and is often doing the opposite, effectively killing possessions.

But the problem with Anderson isn't his fault. He's a glue guy, but he's being used off the bench -- and you can't be a glue guy as a reserve. To understand the difference, look at how Ginobili plays when he's out there with Kawhi Leonard, LaMarcus Aldridge and Tony Parker compared to how he plays with Mills, Boris Diaw and David West. With one group he's complementary, especially when other people have it going. He swings the ball around, takes open shots if they present themselves, but mostly he's just a cog in the machine. But with the reserves, he's the guy. He always has the ball and he's always making things happen. Playing with less talented players, Manu has to do those things. Diaw also defers more while playing with starters than fellow reserves.

Playing in bench-heavy lineups, as Anderson or Simmons almost always are, requires them to be the energy guy who's bringing it for five-minute bursts. Anderson plays like a fifth starter, who's best playing with four highly talented guys. He could be Harrison Barnes on the Warriors and nobody would notice. But as a bench guy, he looks sleepy more often than not and possessions are dying as he passes up shots or hesitates. There is less margin of error for the reserves. They need to take the first good look available because they don't want to get late in the shot clock with guys who can't create for themselves. The "Foreign Legion" inherently understand this and that's why their names are all over the the lineups who play at the fastest pace for the Spurs.

While you scan that list, you'll notice the difference in net rating when Simmons plays with the second unit (14.2) to when Anderson plays with it (2.8). You may also notice how effective Anderson has been, albeit in a tiny sample size, playing with the starters in Leonard's stead. With Kawhi, the Spurs are set at small-forward for the next decade, but Anderson would fit well on a team who has a hole at the three spot. Places like Chicago, Toronto or the Los Angeles Clippers.

There are no such concerns about how Simmons fits. He looks to be Ginobili's successor, with the game and temperament of a classic sixth-man. Whatever tentativeness he had in the preseason, he got over it quickly. He's played 130 fewer minutes than Anderson but he's attempted seven more threes, two more free-throws and has only taken four fewer shots overall. The two are tied in assists. To be fair, Simmons has more turnovers in those 130 fewer minutes and he's the more reckless player, but he's not afraid to make things happen out there and not awed about sharing the floor with future Hall-of-Famers. Pop doesn't have to wonder whether he'll be ready to compete when he subs him into a game.

Simmons is playing like a 26-year-old rookie who had to try out for the Austin Spurs and isn't about to take the realization of his lifelong dream of being in the NBA for granted. He's fought his way into the league and fought his way off the Spurs' inactive list and into the rotation.

And this is the ironic key to being successful with the Spurs. For all the rhetoric we've heard and read over the years about how guys must be coachable to play for Pop, I've always thought the opposite was true. He wants people that challenge his perceptions of them, that prove they're better than he thinks they are. That's how they earn his trust and get playing time, shots and acclaim. The players who don't challenge him, the ones who settle into the "slots" Pop has for them and don't make waves, they seem to find a way of having those slots shrink over time and wind up being former Spurs, like the small-forward who was around before Leonard.

Anderson is certainly an NBA-level player who has a future in the league, but to have a future in San Antonio he needs to be ready to evolve.