The guy who is the best fit for the Cs is the guy who ultimately ends up being the best player. When you're talking about a potential high pick, you take the best talent. Doesn't matter who you have on your roster. Trust Danny Ainge to recognize the BPA and take him.
If Embiid is the next Hakeem, you always take the next Hakeem. If Danny thinks Parker is the best guy, take Parker. When you take picks based on fit at the top of the draft, you end up with Darko's and Marvin Williams's.