Looking at the players picked after Primo, there's not too many whose stats or contribution stands out apart from these guys:
13) Duarte - 13ppg, 39 starts, 55 GP, garbage Pacers team, 5 years older
18) Tre Mann - 10ppg, 26 starts, 60 GP, beyond garbage OKC team, 6'3 PG not needed on Spurs roster
26) Bones Hyland - 10pts, 69 gms, another 6'3 PG see above
35) Herbert Jones - 9.5pts, 69 starts, great 6'8 PF defender, 4 years older, who could've seen him coming anyway
Based on that it's nothing to judge him harshly at this point. He's got just as much chance to succeed as any player picked after him.