The 1997-98 NBA season had little in common with today’s league. There were teams in Vancouver and Seattle; the Warriors were lousy and won only 19 games; and the Utah Jazz shared the NBA’s best record while hitting just 3 threes per game. But the one thing that was the same then and has never changed: The Spurs won at least 50 games.San Antonio’s regular-season success has been so consistent, we’ve all largely come to assume it over time. The only year the Spurs didn’t win at least 50 games in the past 20 seasons was 1998-99, when there were only 50 games total because of a lockout: San Antonio won 37 games and the NBA title. And given the club’s relative roster stability this summer after last year’s 61-win campaign — one in which a legitimate superstar was born — it would seem prudent to expect another such year from the team in silver and black.But if there’s ever been a season to wonder whether the Spurs are due for a real regression toward normalcy, this may be the one.Player health could loom larger than usual this year for San Antonio. The team will begin the regular season without Tony Parker and Kawhi Leonard, who was held out of the preseason and now will miss at least the season opener because of a right-quad injury sustained last season. A lack of athleticism on both ends of the floor, particularly if Leonard is forced to miss significant time, figures to stand out more this season than it did last year after a couple of free-agent defections.And it’s unclear how much longer the Spurs can keep finding moderate success with players who, at least in some ways, seem to go against the grain of the analytics movement that the club has been at the forefront of.Heading into the start of this season, FiveThirtyEight’s NBA predictions1These are compiled by mixing team and individual-player ELO ratings. peg the Spurs at exactly 50 wins — tied for fourth with Minnesota, an up-and-coming team that may have its own growing pains, and just one game ahead of the Denver Nuggets, who are estimated to finish No. 6 out West. Only the Atlanta Hawks (projected to have 17 fewer wins) and Chicago Bulls (-14) — teams that started the rebuilding process this summer — are projected to have steeper drop-offs than San Antonio’s 11-game decrease. And if anything goes wrong for them, the Spurs could easily miss that 50-win mark.Spurs coach Gregg Popovich has never been shy about resting his best players. But being down two starters to begin a season would be navigating uncharted territory. (No public timeline for a return has been set for Leonard.) As such, longtime Spur Manu Ginobili acknowledged that San Antonio might be a bit slower out of the gate this season while teammates try to develop a rhythm without two key players. “We are not going to start full-throttle,” he said. “We’re not going to start as ready to compete as in previous years. But we’ll figure it out.”The Spurs will have to learn how to create offense without two or three of their most aggressive scorers from last season. Parker, Leonard and Jonathon Simmons, who’s since joined the Orlando Magic, accounted for a whopping 68 percent of the team’s drives to the basket on a per-game basis.2Ginobili had the fourth-highest rate among Spurs’ regulars, at just 2.6 drives per contest. If both Parker and Leonard are simultaneously forced to miss considerable action, it would put a strain on their teammates, who, despite boasting some of the best 3-point shooting in the league, aren’t necessarily the best shot creators.Video Playerhttps://fivethirtyeight.com/wp-content/uploads/2017/10/spursawry.mp400:0000:0000:00Use Up/Down Arrow keys to increase or decrease volume.Video Playerhttps://fivethirtyeight.com/wp-content/uploads/2017/10/greendrive.mp400:0000:0000:00Use Up/Down Arrow keys to increase or decrease volume.There’s also the question of whether some of San Antonio’s players are meant to play specific roles — ones that only work with teammates who accentuate their best attributes. Patty Mills, who had largely perfected his gig off the bench, is the best example here. Mills is a dangerous spot-up shooter off the bench, but he hasn’t proven capable of truly running an offense himself for more than a minute or two at a time.Video Playerhttps://fivethirtyeight.com/wp-content/uploads/2017/10/millsstripped.mp400:0000:0000:00Use Up/Down Arrow keys to increase or decrease volume.Part of what sets Mills apart is the frenetic pace at which he plays. He ranked among the NBA’s top-five players in terms of how fast he moves around the court in each of the past four seasons. Yet the energy it takes to play as fast as Mills does — he basically plays a high-speed version of the playground game Tag in order to get open shots — can only be provided in spurts.Video Playerhttps://fivethirtyeight.com/wp-content/uploads/2017/10/millsexhausted.mp400:0000:0000:00Use Up/Down Arrow keys to increase or decrease volume.Because of how deep the Spurs have historically been, spurts were generally all they needed from Mills. But with Parker out another month or two, that will change this season.To be totally clear: None of this is to suggest that the Spurs won’t be a good team this year. They just may not be Spurs good. If there’s a team that can overcome these sorts of flaws, it’s one coached by Popovich, who regularly motivates his teams not only to play above their heads but also to adapt from year to year to the ever-changing NBA. (FiveThirtyEight’s preseason forecast had the Spurs winning 52 games last season; they blew that out of the water, winning 61 games.)The vast majority of their league-best defense is still intact. And the team’s basketball IQ — for example, its ability to know exactly who to leave open, evidenced by its league-best defense against corner threes — is uncanny, sometimes making up for what the Spurs lack in athleticism. While the Spurs didn’t land Chris Paul this summer, convincing Rudy Gay to sign on was a coup — he’s someone who can help fill in for Leonard if need be and reasonably match up as a small-ball power forward against teams like the Warriors and Cavaliers.The Gay signing fit a recent trend for the Spurs, one that both explains how they’ve remained contenders and illustrates what could end up making them mortal again at some point: San Antonio has developed a knack for picking up players who aren’t necessarily a perfect analytical fit based on where the league is headed.LaMarcus Aldridge, for instance, joined the Spurs in 2015, right after he’d fired up a league-high 11.1 shots per game from midrange — a look today that’s widely considered to be the most inefficient shot on the floor. Upon leaving the Trail Blazers, he said he didn’t want to play center exclusively, even as scores of power forwards have made that shift in light of the small-ball movement. Yet the Spurs got considerable mileage out of him despite his inefficiencies and did so by playing him often at the center position. A year later, they added Pau Gasol, who also seemed a dubious fit because of his lack of defensive mobility. But San Antonio, which deserves credit for allowing Gasol to let it fly from 3-point range, also managed to withstand his defensive shortcomings as the team logged the league’s best defense last season. (The Spurs surprisingly gave the 37-year-old Gasol a new three-year, $48 million contract this past summer.)Gay fits better than either Gasol or Aldridge did, both in terms of his contract and his playing style. But it’s also not clear yet whether he’ll be himself, given that he’s coming off an Achilles tear. He played well the past few years but did so for losing teams out in Sacramento. Before that, the analytics friendly Grizzlies and Raptors both dealt him away and then immediately saw their on-court product improve.The Gay signing is the type of head-scratcher that the Spurs have proved their doubters wrong about in the past. But at some point, going against the grain will stop working for the Spurs. And between those gambles and the injuries to Leonard and Parker, there may finally be enough loose strings to bring San Antonio’s amazing 20-year run to an end. After all, no team — not even the Spurs themselves — can be Spurs-level good forever.Check out our latest NBA predictions.