In the lead-up to the 2013-14 NBA season, Grantland will examine key players — X factors — for contending teams. The series begins today with the San Antonio Spurs’ Kawhi Leonard.

The lasting image of the 2013 NBA Finals, an all-time classic series, will always be Ray Allen’s season-saving corner 3 — a shot both impossible and inevitable, ludicrously difficult under the most intense pressure that can exist, but also a shot you (and he) could map out in your brain the minute Chris Bosh rebounded LeBron’s miss with Allen just to Bosh’s right. It was probably the single most important shot in NBA history, and indisputably the most painful moment in the Spurs’ franchise history.

But the second-most potent image from that series gives San Antonio legitimate hope that 2012-13 wasn’t the last gasp of a proud, aging group. And that image is: HOLY CRAP, KAWHI LEONARD.

Leonard was wonderful all season, at least when he was healthy enough to play. But his seven-game, two-way masterpiece against Miami was a discrete event that changed the perception of Leonard both leaguewide and within the Spurs. Parts of his game that had emerged only in tantalizing glimpses burst through when the Spurs needed them most: against an elite defense that brings a destructive speed for which it is almost impossible to prepare, and with Tony Parker ailing in the back half of the series. Manu Ginobili wilted against the Heat’s blitzing defense; the Spurs simply would not have survived without the emergence of some other creative force.

Leonard supplied it. He used his rebounding to manufacture offense with coast-to-coast adventures once permitted only for Parker and Ginobili. He attacked off the dribble much more aggressively for floaters and drives at the rim, though always within the flow of San Antonio’s motion offense. He took six shots working as the screener in pick-and-roll plays — normally a big man’s job — after attempting just three such shots combined during the regular season, per Synergy Sports. He posted up Mike Miller, a carryover from doing the same against smaller Golden State players in the conference semifinals.

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He embarrassed LeBron James and Dwyane Wade on the offensive glass, outworking them for essential second-chance rebounds and then making heady scoring cuts into open spaces during the ensuing chaos. How was this even allowed on a team that pioneered the idea of punting on the offensive glass in order to get the heck back in transition defense? “If there was one area where we did have high expectations for him,” says R.C. Buford, the Spurs’ longtime GM, “it was offensive rebounding. And that was a bit concerning, because we’re not an offensive rebounding team. We’ve never been an offensive rebounding team with our [small forwards]. Bruce Bowen was always the first man back on defense, and that allowed for more penetration from Manu and Tony.”

Offensive rebounding wasn’t the only un-Spurs-ian thing Leonard pulled when the stakes were highest. He sought easy baskets by leaking out early from defense to offense, sometimes even before the Spurs had secured a defensive rebound — a once-unthinkable no-no for a key rebounder on a Gregg Popovich team. He gambled for steals, bending or breaking classic San Antonio rules that emphasize sound positioning over risk. Leonard won a huge percentage of these bets because he has a sophisticated and hard-to-teach understanding of when in-the-moment conditions — the placement of each player, the trajectory of the ball, the location of a shot — increase his odds of success. What appears reckless is not necessarily so for a player with brains and athleticism. Leonard in this way is the heir to Ginobili as the Spur to whom traditional Popovichian precepts do not always apply.

“Those aren’t really Spurs things,” Leonard says with a laugh. “But as long as I’m in my spots on the defensive end, Coach gives me some leeway now.”

The Spurs need this Finals version of Leonard, this all-around force, to emerge as a consistent weapon if they want to make yet another improbable push for a championship. The field around them is deeper, in both conferences, and there will come a day when age really does take a permanent bite out of Tim Duncan. Manu Ginobili looks great right now by all accounts, but he has never been more vulnerable to the combination of age, lingering injuries, and ultra-athletic defense that disrobed him for all but one game of the Finals. We may have already seen the offensive ceilings of both Tiago Splitter and Danny Green, and none of the other young pieces here look ready to make a huge contribution against the best postseason competition.

That leaves Leonard as a bit of a wild card, and his performance in the Finals earned him the trust level necessary — from Popovich and the Big Three — to stretch himself on offense in the coming season. “There is no doubt,” Buford says, “that Pop now has the confidence in him to expand his role.”

“Hopefully I’ll get some plays called for me,” Leonard says, chuckling again.

Popovich will call plays for him, and perhaps even end-of-game plays, but that’s not really the point — and Leonard knows it. The Spurs are a system team, not a play-calling team. They run a continuous, side-to-side motion offense centered on Parker’s pick-and-roll brilliance, canny screening from Duncan and Splitter, Duncan’s post game, and killer spot-up shooting. The Spurs at first limited Leonard’s involvement within that system to standing in the corners and shooting open 3s — even though they had no clue when they drafted him, just before the lockout, if he’d turn into an even serviceable 3-point shooter. “Our expectations weren’t necessarily for him to be a 3-and-D guy,” Buford says. “His track record didn’t lead you to believe he could extend out to the 3-point line. I don’t think any of us thought he was going to be this kind of building block for us.”

But the Spurs’ offense, just through the automated whirring of its parts, spits out opportunities for Leonard to catch the ball and do something with it. And if he can do more stuff when he does get the ball within the workings of that system, it will mean Duncan, Parker, and Ginobili have to do a bit less. It will make the Spurs a hair less predictable. It will put a crucial bit of increased mental and physical stress on defenders who have to be concerned about another damn thing the Spurs might do. It will limit the number of possessions on which an aging Spur has to create something, anything, with the shot clock ticking down.

That stuff can be small, and hard to spot, and it may not show up at all in the Spurs’ big-picture metrics — which have been beyond healthy for years. But it’s the kind of in-house evolution that becomes crucial when you’re trying to squeeze out enough points for 16 postseason wins against a gauntlet of defenses that might include Houston, Memphis, Miami, and other potentially elite outfits.

Here’s a simple example: A lot of Spurs possessions include a classic Utah-style “flex” sequence in which Leonard will set a pick for Duncan under the rim, dart out toward the perimeter around a pick set for him at the foul line, and then catch the ball about 20 feet from the rim:

The sequence isn’t really designed for Leonard; he might not even catch the ball if his first pick for Duncan hits flush enough to spring Duncan for a post-up on the block. And if Leonard does get the ball, as in the photo above, his first job has typically been to reverse the ball back to Parker on the wing so that the machine can continue on to its next phase.

But there is system-based opportunity for Leonard here. When Leonard makes that catch, the Spurs’ second big man is usually lurking nearby, ready to set a screen for an impromptu pick-and-roll if the situation favors it. Leonard took only 49 shots out of the pick-and-roll all season, per Synergy; what if he can do a little bit more?

In a similar vein, the Spurs’ offense also features sets within sets that involve Leonard starting in the left corner, jetting around two picks, and catching the ball near the left elbow:

We’ll see more of that this season, and the Spurs will give Leonard freedom to attack if he can find a crease.

Leonard is at the top of the arc, having just passed the ball to Parker on the left wing after Parker had scampered around two screens — a reliable move that triggers a lot of San Antonio possessions by getting Parker the ball on the move with a head start on his defender.

And Kevin Durant, guarding Leonard, has thwarted option no. 1, a Parker drive, by sliding down from Leonard and planting himself at the foul line. Parker’s natural next move is to kick to Leonard up top, continue running around to the other side, and catch the ball again.

But there’s a built-in second option here: Duncan, standing near the right elbow, can move up to set a pick for Leonard so that Parker’s pass leads right into a fast-moving Leonard-Duncan pick-and-roll.

The Spurs’ half-court offense doesn’t relegate Leonard to Bruce Bowen duty. Instead, it quite naturally produces chances for him to work off the dribble. This is where Leonard has only begun to prove himself, and it’s the area of his game about which talent evaluators were most skeptical ahead of the 2011 draft, according to several executives whose teams picked near the middle of the first round. Leonard’s a good athlete, but not a devastating one, and teams were concerned he would not be able to blow past (or over) NBA athletes.

And the thing is, they were pretty much right. Leonard has a hard time creating meaningful separation off the bounce, and though he’s capable of highlight facials (ask Mike Miller), he’s not yet an explosive off-the-dribble threat. (As an aside, I asked Leonard how it was possible to have literally zero visible reaction to cramming on poor Miller like that in the freaking Finals. Leonard’s response: “I’ve dunked on a lot of people, so there wasn’t really a reaction I had.” OK!)

But he has learned to compensate with trickery and a well-honed sense of how to use a defender’s momentum to his own advantage. If Leonard drives hard to his right and senses his defender sliding hard in that direction to keep up, Leonard will stop on a dime, watch that defender keep on sliding toward the baseline, and rise up for an easy floater. He can work the same trick, only with a right-to-left Euro step:

And if he’s driving left, Leonard can stop, pivot away from the flailing defender, spin to his right into the paint, and toss up that same floater. Basically: Leonard’s go-to move is stopping, and he has used it to create openings he can’t create the way a superstar might. “People in the NBA are just as athletic as you,” Leonard says. “That’s the game. You have to have the change of pace. You have to change speeds to get around people.”

Now the Spurs need to see if he can do it over the long haul, and against defenses that will pay him more attention. Nobody knows the answer. The glimpses are promising, but they are just glimpses, and Leonard has shown very little ability to throw effective passes on the move at the NBA level. Leonard averaged fewer than two assists per game last season, which is a very hard thing to manage for a perimeter player logging 30-plus minutes a night. Only 17 players leaguewide last season managed that double — at least 30 minutes per game, fewer than two dimes — and 13 played either power forward or center. In other words, they were big-man finishers — Omer Asik and Tyson Chandler types. The remaining four players were a catch-and-shoot specialist (Kyle Korver), an aging wing who logged significant time at power forward (Metta World Peace), a general non-threat with the ball (Alonzo Gee), and Leonard.

That’s not necessarily a damning thing; the Spurs have given primary on-ball duties to other players during Leonard’s brief career, deflating his assist numbers. And Leonard reads the floor when he’s holding the ball on the perimeter, monitoring the movements of nine other players, and even when he catches the ball in traffic after a cut.

But he has done very little passing off the dribble as a primary option, both one-on-one and via the pick-and-roll. In his limited chances, he has focused on scoring, and he’s shown a tendency on the pick-and-roll to pull up early for long 2-point jumpers — shots that come before he has really punctured the defense or engineered open passing lanes to shooters. The Spurs always have shooters someplace, but Leonard has to prove he can find them with the kind of rapid-fire, inside-out passes Parker and Ginobili use to generate open 3s. The same caveat applies to his burgeoning post game.

One area in which Leonard definitely can pass: in transition, when the floor is a bit clearer. And that’s another phase in which Leonard might naturally grasp a larger role. Per Synergy, about 22 percent of the possessions Leonard finished via a shot or turnover came in transition, a very large share and the highest among all Spurs — even the roadrunner Parker. Duncan and Splitter both run the floor hard, so that even if a Leonard fast break doesn’t lead to a shot, it could easily flow right into a pick-and-roll in semi-transition — that sweet spot early in the shot clock when the defense is still scrambled. The Sixers, for instance, stopped Leonard on this attempted break, but what if 2014 Leonard is more prepared to create something off the impromptu pick-and-roll Duncan offered here with 18 seconds still on the shot clock?

Again: It’s a little thing, a play that might happen just once or twice a game. But the expansion of Leonard’s offensive game amounts to hundreds of such little things over a season, with the end result being a healthier, more well-balanced team unleashing more varied means to attack primed postseason defenses.

You’ll note we haven’t discussed Leonard’s defense. There isn’t much to discuss. The guy is already insanely good, though I’m sure the San Antonio coaching staff finds places to nitpick here and there — an ill-advised gamble, a back screen that catches him peeking at the ball and unprepared, a less-than-urgent response to a cut.

But that stuff is rare, and Leonard is so long, and so wonderfully balanced, that he can recover almost immediately from an early hiccup that leaves him a half-step behind. He is like a phantom, slithering between and around bodies, appearing on the other side of screens that looked to be insurmountable a half-second ago.

You know of whom he reminds me in terms of on-ball defense? LARRY SANDERS! In discussing the extension SANDERS! signed with Milwaukee, I noted that point guards who tried to get him off-balance on the pick-and-roll, as SANDERS! slid over to contain them, just couldn’t do it. If they threw a hesitation dribble at him, SANDERS! acknowledged it by moving slightly in the direction of that dribble, but no farther. If they gave him a head fake left, he’d take a mini-step there without lurching or losing his balance, so that he was still right in front of the point guards upon their inevitable crossover dribble.

It looked as if point guards were trying to dribble by a mirror image of themselves. Leonard is like the wing version of SANDERS! in that regard. His movements are so in sync with ball handlers — from LeBron James to Tayshaun Prince — that it almost appears as if he’s moving exactly in concert with them, instead of in reaction to their moves. He’s always on his toes, always on balance. Leonard credits his ability to mimic opposing ball handlers to his years playing defensive back in football through high school, responding to every move wide receivers made without falling behind. “Playing football helped me a lot,” he says. “Just reading the quarterback’s eyes and reading receivers, figuring out what they want to do.”

Every perimeter defender in the NBA falls behind now and then; that’s the entire point of a pick, after all. But Leonard stays closer than almost anyone, and even when he has to trail a guy around a pick, Leonard’s arms are so long that he can challenge shots from behind:

Bottom line: His defense is already elite. His ability to reach a new level on offense, and with the ball in his hands, will be a huge factor in determining whether the Spurs get a chance to nab the ring they barely missed last season. Even being in the title conversation is a win for the Spurs in the big picture, considering Duncan is 37 and Ginobili 36. They needed Leonard to stay in that stratosphere last season, and they’ll need even more from him to win their fifth title in franchise history.