I'm not totally sure about this but I think the Spurs didn't start going all lax on the regular season in order to save their energy for the playoff stretch until a season or two after their most recent title in 2007. That said, they've had a recent history of not going full tilt until at least 30 games in and it's either helped them continue to make deep playoff runs in spite of an aging nucleus or cost them titles by preventing them from getting the top seed in all but two of the past six seasons (2010-11 where they ironically lost in the first round anyway and 2011-12 where the Thunder got 'em in 6)
Without being aware of the injury issues they faced in each of those years, it's difficult for me to know for sure which side of the argument has more of a foundation but if they are trying to save some energy for the stretch run by only giving 70-80% during the early season, it certainly bit them on the ass last year considering how close they were to closing out the Heat and how having game 7 at home would've been a monumental advantage for them. Yeah, it was a freak of postseason probabilities for the Heat to come back and win game 6 the way they did but chances are that kinda thing doesn't happen with 20,000 roaring opposing fans bearing down on the Heat.
This established, I think until we see the Spurs make it to the 30-game mark with at least 20 wins, it's hard to know if they're truly gonna be able to win Timmy his 5th.