I just did a run down of the Heat's best lineups in the regular season and in the playoffs and every one in the top-25 had Whiteside or Bosh (regular season) on the floor. So I'm not sure where you are getting this from. You can say you watched it in the playoffs all you want, but you have literally zero proof to back it up. BTW, I stopped after the top-25 because after that it's pointless when not one lineup had Deng as the tallest player on the court.
Yes, of course the Heat are better with Bosh or Whiteside, but obviously those guys arent always able to be on the floor because of health. I never once said I want Deng to be playing center, but it's something he can do if necessary (vs select matchups I believe it could be a good lineup, like playing against the Warriors if they have Green at center). They were forced to do it vs the Raptors and it didnt work as well because they play true big men, but it was good vs the Hornets when they employed it.