Turnovers + rebounding
Getting killed in possession creation. Minus 5 in turnovers and minus 4 in rebounding. 9 possessions a game. Very difficult to win when you give your opponent 9 extra possessions a game to score on you.
I don't think we've been as bad rebound-wise as the stats show, or as you seem to allude. For consideration, we have played 3 teams that are in the top 10 of rebounding differential.
The other was Milwaukee, who we out rebounded by a wide margin.
This early in the season, outrebounding us by that much is a huge part of why they're in the top 10 for differential. Can't disentangle the two with such a tiny sample. Unless you meant last season's differential?
Overall we've looked very poor on the boards, largely because our bigs are a mix of undersized (Sully+Bass), undermuscled (Olynyk), and inexperienced at the NBA level (Sully, Oly, + Faverani).
No, this season, and Toronto for example has out rebounded other opponents by a wide margin as well.
Detroit has a lot of good rebounders there, so no we're not the reason.
Memphis the same...
So no, they're not up there due to us. More like we're "down there" because of them more than anything.
Rebound differential is calculated based on the games a team has played. When a team has played only 3-4 games, and one is against us, their differential against us is having a major impact on their overall differential. That's how the statistic works.
One way to get around this would be to compare differential against us to overall differential:
Toronto - Overall differential +14; vs us +15. Difference = +1
Milwaukee - Overall -12; vs us -11. Difference = +1
Detroit - Overall +5; vs us +7. Difference = +2
Memphis - Overall + 2.8; vs us +4. Difference = +1.2
Average: +1.3 better vs us than overall.
Every team we've played has outperformed their overall average differential against us. Conclusion - we kinda suck at rebounding.
There's a lot of aspects pulling at the stats, as you mentioned, small sample size. Like Detroit and Memphis playing against each other understating their rebounding prowess, while punishing us for outrebouding a team by 11 because they got outrebouded by a wide margin by the current #1 team in differential with Toronto (which in turn might explain how inflated their current performance is, in part because our rebounding performance in the first game was abysmal).
So, I stand by my assessment that our team hasn't been as bad rebounding the ball as the stats show, except for that first game performance which was an aberration.
We'll see how the season progresses. I don't expect us to be rebounding leaders, but also not the bottom rebound feeders the stats show.
Also, Sullinger has played limited minutes so far, and wasn't around in the first game... so food for thought on that regard.