O'Bryant is far more skilled than D.Jordan, and a similar freak athlete. I'd much rather have the guy who could be approaching the point where he breaks out and becomes a real NBA contributor, rather than the guy who's just starting that climb and is probably at least 2-3 years away from helping a good team.
POB is going to be a very good shot blocker immediately, and he dominated at both ends in the D-League last season (a FAR higher level of competition than even the best NCAA ball, especially for a center) so he's ready to be fighting for rotation minutes in the NBA at this point.
As for POB's HS ranking, I'd say two things: First, he was never talked about as a top-level recruit coming out of HS, which is why he ended up at Bradley. He was still mediocre for a year or two in college, too, and then he figured something out, and started kicking butt and taking names at the NCAA level. He was still relatively unproven, but he was at least periodically dominant in college.
Minnesota is also a tough HS region for unpolished big guys to get noticed, because while the overall talent pool isn't great (it's really pretty good compared to overall population, but not great) there is a TON of size here. Most good HS teams in the Twin Cities metro area (Blaine is a suburb of Minneapolis) play NCAA-sized frontlines, with 6'4"-6'6" small forwards, and two guys bigger than that. A legit 7-footer isn't particularly out of the ordinary here, so POB wouldn't have stood out just because he was big, like he would have in most parts of the country.