One problem with that theory is that Olynyk clearly wasn't NBA ready until after the All Star Break. If you want a recent four year player that was, try Damian Lillard.
The thing about four-year players is that they're not typically expected to become that much better than they already are.
Big men often take longer to physically develop than guards, and they improve more as they finish developing. This tendency is part of why the rookie of the year award is usually won by smaller players.
Nerlens Noel is going to be much better at age 24 than he is now.
Olynyk is going to be significantly stronger this season than he was last season, and that shouldn't surprise you or raise your skepticism.
Olynyk's skill set was incredible coming out of college, it was very much NBA ready. Guys whose games rely on a high skill level are more vulnerable to rookie struggles like Olynyk had at first. We see this all the time, especially with shooting guards whose game relies not upon great athleticism but high skill and finesse.
Players who rely predominantly on athleticism are more immune to a bad rookie adjustment period, because their game doesn't require the confidence that finesse players must gain to make an impact.
Without confidence, a finesse game falls apart much more so than athleticism. A guy like Mason Plumlee's game doesn't rely on high confidence to be effective, so he was more immune to a rookie adjustment period.
Look at the other high skill/finesse players in that draft. McLemore, KCP, and CJ McCullum all didn't have great rookie years, especially at first, because that's what often happens with finesse players.
Olynyk saw his confidence surge more than those guys later in the season, but those guys will come along.