Horford also isn't the rebounder Sullinger
Put Sully along Milsap and he would not get as many rebounds as Horford did. Horford for his career is a better rebounder than Sully. It was only when Milsap came that his numbers dipped. Relax, all the teams passed on spending big bucks on Sully, it is going to be ok. Our rebounding will be ok, Horford only averaged one less RPG and he can block shots and shoot better than Jared.
For arguments sake, Horford is not a better rebounder than Sully for his career.
Sully's career average per 36 is 11.1 rebounds per game with a 17.1 rebound %.
Horford for his career averages 9.1 rebounds per game with a 15.4% rebound rate.
Last season Sully averaged 12.7 rebounds per 36 with a 17.1% rebound rate.
Horford averaged 8.2 rebounds with a 12.4% rebound rate.
You can argue that playing with Millsap hurts Horford's numbers, but Sullinger played away from the basket for significant minutes on offense, which hurts his.
Although Horford is still an upgrade at almost every other facet of the game, Jared Sullinger is a better rebounder than Horford.
It's a little unfair to use per-36 for Sully, because he's neither averaged anywhere near those minutes nor can he with his weight. His stamina just isn't there with his weight, so it doesn't really matter if he has a higher per-36 rebounding percentage and/or numbers if he can only effectively play 25 minutes a night compared to Horford's 36 that he can actually play.
That said, we'll see Horford's rebounding numbers significantly increase this year without having to compete with Milsap and splitter for boards. I bet Horford averages somewhere around 17.5 and 9.5 this year.
That's not true - it isn't unfair to use those numbers at all.
Why?
Because the question isn't "who will record more rebounds?", it is "who is a better rebounder?".
If you want to determine who is a better rebounder, you have to look at rebound rates, not totals. How much those players are on the court is irrelevant to this specific argument. What we are asking is which player collects more rebounds WHILE they are on the court.
The answer to that question is Jared Sullinger.
The average rebound rate for an NBA center is around 15%. Horford has not averaged singificantly above that since around 6 years ago, back in 2010/11, when he was 24 years old. He has managed a rebound rate of >15% only once in the 5 years, with his overall average (13.8%) over that stretch being significantly below average for an NBA center.
Jared Sullinger has played only four NBA seasons, and the lowest rebound rate of his career was 15.5%, averaged in 2014/15. He has otherwise averaged 17.5% (12/13), 16.7% (13/14) and 18.7% (15/16).
You also dramatically overrate Paul Millsap's impact on rebounding. Over his career Millsap has averaged only 9.2 Rebounds Per-36, compared to Horford's 9.6 Rebounds Per 36. Millsap's career rebound rate? 15.0%, which is a tad lower then Horford's 15.4%.
To put that into perspective, Amir Johnson averaged 9.2 Rebounds Per 36 with a rebound rate of 14.9% for his career. Pretty much lineball with Millsap, and barely a smidgen below Horford.
Millsap is a solid rebounder, nothing more. He's certainly nowhere near good enough to justify Horford's massive rebounding drop over the past 5 years.
Neither of the two is on Sullinger's level, and that's coming from me - let's just say I am hardly Sully's biggest fan.
I'm not being negative here, I'm just being realistic. As it stands right now, Amir Johnson and Jonas Jerebko are our two best rebounders. Unless Horford suddenly returns to his 24-year-old form, rebounding is going to be a significant weakness for us.
We just have to hope that our quick-strike offense, smothering defense and lightning fast transition game can give us enough of an advantage to offset that weakness.