No offesne but Boris had 5 Diengs in every finger. Actually, they're pretty different players. Boris was MVP of the french league at 18 and was already a do-it-all BB scientist... Dieng is a still very raw, soft young player, with a suspect/work in progress shoot, limited off ball game (questions on his BBIQ)... He is the definition of potential, basically due to his size (that can actually become a disavantage since he wouldn't be quick enough for a wing and too soft for a big in the NBA) would take years to develop or not...
He's not that high regarded in France, and definitely not like TP, Boris or Batum at his age, but precisely preceived as a raw player with potential, which we know NBA GMs are obsessed with nowadays.
So yeah, you're right... Maybe taking a flier on him at 20 or 25 but in a draft where spurs can't afford to fail, it's a huge pass on Dieng at 9. Too risky.