Spacing heat map rankings:
1. Bucks
2. Celtics
3. Warriors
4. Rockets
5. Hawks
26. Spurs
San Antonio were the 26th-ranked team during the regular season when it came to spacing, but if you were to compare their starters v. starters from the across the league, not only would they have ranked dead-last, but the margin between them and the second-worst team was greater than the 1st and the 20th-ranked starters.
Purely from a strategical standpoint, the Spurs' starters offense operated on a level that would've befitted play during the 1990s - light years
behind today's league.
Shot generation v. defender rankings
1. Bucks
2. Celtics
3. Hawks
4. Nets
5. Jazz
29. Spurs
San Antonio were the 29th-ranked team during the regular season when it came to generation of shots, reiterating their inability to generate good* shots [good = uncontested and defense out of position], reflected by their overreliance on activity in the midrange, in a climate where defenses are typically stretched beyond the arc, which made it easier for their opposition to defend their offense (as opposition defenses usually are covering more ground and making more defensive adjustments against teams who shoot higher volume 3s - opposition defenses traveled less distance on defense against the Spurs than any other team during the regular season).
Basically, SA's
pro tem offense was based on their players' talent and ability to generate points in ISO; off-balance/non-set, contested shots; heavy traffic; less space to work in - in spite of their offensive scheme which was holding them back (lack of spacing and lack of 'good' shot creation). This came to a head during the regular season in the games when they shot less than league-average on contested shots, where they ranked 24th on offense (this is to put into perspective how detrimental their offensive strategy was when they weren't making contested shots - they ranked top-5 in contested shot makes during the regular season, and #3 during the first round - contrary to popular belief that the Spurs lack the talent/personnel to win, they were actually winning/in position to win due to their players' ability to make tough shots, not their scheme/game-plan).
The cutting off their nose to spite their face act of trying to match 33% 3-pt efficiency (which is below league-average as it is) through shooting 50% on midrange shots, not only put themselves at an efficiency disadvantage, but they made an improbable task even more improbable by swimming against the tide trying to get those type of shots off in the first place.
TL;DR - Spurs' offensive scheme is completely outdated; Pop got left behind because he and the coaching staff failed to adjust to the 3-pt climate, and relied too heavily on mid post-ups, DD and midrange spots; the ability of the Spurs' players was the main reason that they were in position to win games, in spite of the coaching.