Stevens is making a virtue of necessity. Yet, there are some advantages in playing without a pure Center. Obradovic played many years in the Euroleague without a Center and he was fine.
What Obradovic did in a league without a defensive three second rule where players generally lack extraordinary athleticism (or size, for that matter) is not particularly relevant.
Stevens is obviously working with what he has. But the fact that the team can't field a better center than Olynyk or Sullinger will never be a virtue.
I wouldn't be so dismissive of such a great coach. In any case, there are plenty of teams in the NBA too that play without a Center. Reason is to get a legit Center you have to pay too a high a price. And you might be better off investing your money in other positions.
Personally I like a lot how Stevens uses Sullynyk in the offense. Victory-wise it will not get us much, but these two guys are developing in a direction that maximizes their respective strengths.
It's a different league. The coaching qualities of Obradovic are not the topic of debate here.
Also, while people insist on lamenting the "lack of real centers in the NBA", the truth is that most teams do have legit centers. That is, players that are big and strong enough to defend the 5 position in the NBA. The fact that most of those players are now skilled enough to not have to depend on brute force on the offensive end is a completely different topic.
Anyhow, here's a depth chart for all NBA teams:
http://www.rotoworld.com/teams/depth-charts/nba.aspx. In my mind, there's overwhelming evidence that the average NBA starting center is bigger than Jared Sullinger, and more athletic than Kelly Olynyk.