9-1 is great. While it's true Spurs have faced low level opponents, 9-1 with 6 games on the road and with these 10 games played in only 17 days, can only be seen as a very good start of the season. Some thoughts on some more specific aspects:
Belinelli versus Neal:
Neal (and Blair, but that's another subject), being an empty stats player that didn't make the team better was reflected in his on/off court stats. During his career with Spurs to offense wasn't really better while he was on the court while the defense was significantly worse.
Belinelli seems to be a way superior team player. That's what the naked eye said and stats confirmed it. His +/- is right now at +10.1 points per 100 possession while Neal was at +4.2 points with Spurs.