One reason I think it’s hard to predict a rookies numbers, is because well they’re rookies, and one of two things usually happens.
1. No matter how good you are, adjusting to the NBA takes time. Rookies tend to start slowly (or are brought along slowly), gradually improving as the year goes on. Many times even high potential rookies don’t start the first 5, 10, 20 games etc., and many times production for rookies doesn’t really take off until the end of the season.
2. They also tend to be inconsistent. Not use to the physical demand, the long season, all the games/travel, whatever. A lot of rookies hit the rookie wall around January/February, and their numbers take a hit.
Most rookies fall into one of the two above scenarios, sometimes both.
Look at the most NBA ready player in the last 20 years, Tim Duncan. His rookie year, even though he was on the All-Everything team (NBA, Defensive, Rookie) that first year, look how his production went: 15ppg in November, 19ppg in December/January, 24-27ppg in February-April.
Another ROY, Kenyon Martin, went from consistently putting up 10-12ppg in November-March, then April puts up 18ppg.
A unique player like Dirk, his rookie year he went from 6-7ppg in the Feb-March, to 11-12ppg in April-May (lockout year).
Greg Monroe went from 4ppg in November, to 6ppg in December, to 11-14ppg in January through April.
While those guys continually, gradually improved as they got adjusted to the NBA, some guys are all over the place (hitting the rookie wall, and still adjusting to the grind of the NBA is what I’d attribute it to).
Yao Ming went from 10ppg in November, to 17ppg in December, back down to 12ppg in January, back up to 17ppg in February, then down to 14ppg and 12ppg in March and April.
You have a guy like Kevin Love. He went from 8.4ppg to 6.6ppg to 12-13ppg to 16ppg to 10ppg from November to April.
Last year’s #1 pick, Anthony Davis, went from 14-15ppg in November and December, dropping to 11ppg in January and February, back up to 16ppg in March and April.
I think very rarely do you get rookies who can come in and pretty consistently put up good numbers all year during their rookie years.
So basically I always try to be conservative on rookies, give them a chance to adjust to the NBA. I think a lot of coaches purposely bring rookies along slowly. Look up most rookies stats. They may play 80+ games but they didn’t start for the first 10,20,30, games etc. (Pretty much the case for most of the guys I’ve listed in this post and my post from the first page of this thread).
I think it’s more realistic to argue Olynyk put’s up some of the loftier expectations in this thread in March and April, but not for the whole year. Olynyk's "unique" skill set isn't going to cause him to avoid the rookie wall or help him adjust to the NBA grind. Give rookies a chance to adjust, expect them to be brought along slowly, and don’t expect too much from them right away.