Even if centers like Whiteside are harder to find and there's no guarantee Russell will pan out?
There's still no guarantee that Whiteside will pan out. Remember, he only has about 1 combined season of NBA experience. There is a reason that Miami was able to get him off the scrap heap and the only reason they did was because they were desperate.
A possible red flag to me would be if Miami were even truly willing to trade him. I'd want to know why. If the reason was that they didn't want to pay him what he'll demand, I'd want to know why they aren't willing to pay him.