As a center, if you are not a 3pts shooter, you need to be able to defend the perimeter well and recover fast in the paint, as well as being a rim protector and a rebounder. Offensive skill is not very necessary (see Zaza, Thompson). But if the center can pass, run in transition and is a descent 3pts shooter, then it's jackpot.
That's why I believe Zizic has even more value than Okafor.
That's how center are evaluated nowadays, but 1 or 2 seasons away, many teams were still in denial.