In looking for indicators to help predicting prospect success I came up with the following hypothesis to test.       
      
"Non bigs with at least average positional size and ESPN recruiting rankings above a 94 are the safest group to draft from"       
      
Looking at prospects from 2014-2018 high school classes (number is their ESPN grade)       
      
2014   T Jones   97
2014   E Mudiay   97
2014   S Johnson   97
2014   J Jackson   97
2014   T Pinson   96
2014   K Oubre   96
2014   D Russell   96
2014   I Whitehead   95
2014   J Winslow   95
2014   J Berry   94
2015   B Simmons   97
2015   B Ingram   96
2015   J Brown   96
2016   J Jackson   97
2016   J Tatum   97
2016   L Ball   96
2016   D Fox   96
2016   M Fultz   96
2016   M Monk   96
2016   F Jackson   96
2016   T Ferguson   94
2016   J Isaac   94
2017   M Porter   97
2017   T Duval   96
2017   C Sexton   95
2017   G Trent   95
2017   K Knox   95
2018   R Barret   96
2018   C Reddish   95
2018   R Langford   95
2018   N Little   95
2018   K Johnson   94
2018   Q Grimes   94 (still in NCAA)
2018   A Simmons   94
      
Obviously there are a range of outcomes and many of these prospects have yet to reach their ceilings but of the 33 listed (Grimes isnt in NBA yet) I would only count 5 (Duval, Berry, Pinson, Whitehead, and Jackson) as non NBA players. Others like Langford, Little, Knox, and Ferguson I am not counting as busts because they have shown glimpses of NBA potential. Of those 33 players I count 12 (Russell, Simmons, Ingram, Brown, Tatum, Ball, Fox, Fultz, Isaac, Porter, Sexton, and Barrett) as having either already made an allstar game or they have the clear potential to make an allstar team or be a high level starter.       
      
      
Looking at the current NBA draft class with the #16 pick the Cs are projected in most mocks to have a few players available who fit this criteria. 
J Johnson, ESPN 94 some mocks have him sliding but I would be shocked to see him outiside the top 10. 
J Springer, ESPN 94 he is quickly becoming my favorite possible pick for the Cs. He is the youngest American in the draft, has great positional size and while not super explosive he is an elite lateral athlete. Waiting for his development is not idea but a Jrue Holiday like ceiling is not out of the range of possibilities for Springer.  
Z Williams, ESPN 95 after a lot of hype he showed flashes at Stanford but in general he disappointed. His shooting % and lack of strength worry me. The lack of strength makes him an unlikely Celtics pick but I would still be fine with the gamble at #16.
BJ Boston, ESPN 96 my feelings on Williams are the same for Boston. He disappointed on college but given the year we just had with Covid I would still make the gamble at #16 or be willing to trade back into the 20s to try to land him.
J Christopher ESPN 95 he had an inconsistent season and was limited to 15 games but showed glimpses of being an NBA scorer. Watching his game vs Villinova it isn't a stretch to imagine his ceiling be a 20ppg NBA player.  
* G Brown ESPN 95 he is a tougher one to predict in that he may be more of a PF then a wing in the NBA and will need to add strength to make that work. Of the 6 prospects I have listed I would gibe Brown both the highest ceiling and the lowest floor. 6'9 super athletes who can shoot the 3 are so valuable in the NBA that he is worth the gamble but I can see his development taking a while and the team will have to be patient.