First of all, the Spurs tried a lot lineup combinations so far; in first 23 games, Gregg Popovich sent out on the floor 204 different 5-man units. In comparison with other 5 top-seeded teams in the league, it’s the most by far margin.
Warriors, who also changed their roster significantly, tried out 163 lineups. Cavaliers came out with 132, Rockets with 112, Clippers had 99 combinations, and Raptors 88.
This number itself shows that Spurs are still searching, still figuring things out. Obviously with this much changes during games, on-court chemistry is suffering.