I realise that, as does pretty much everyone on here, and that's why I began with "If we're talking fit ..." It's a 'for the sake of discussion' topic.
The overriding aim is, as you point out, draft the best player possible or trade if the value offered is better. FWIW I'm torn on who that BPA (1st pick) is ... currently somewhere between Noel & McLemore with Bennett being the wildcard. A further FWIW ... I worry about Shabazz being able to guard the 2 & don't see Len or Zeller as top 5 players.
I agree with pretty much all your assessments. I think Zeller will be solid off the bench and Len will be picked high because of his length but he won't be much in the NBA. I won't be surprised if Bennett slips to 10 and possibly later in the lottery. His height and lack of defensive effort are really going to hurt his draft stock IMO.