It's way too early to write off these guys after one season. I've been guilty of it myself...many, many times.
Most of these guys are only 19 or 20 years old when they come into the league (if they're already 22 or 23 coming into the league, that changes the timetable for judgment). Some of them will never pan out, while others simply need time.
Fit matters, too (coaching, roster construction, etc.). I'm not driving the Aaron Gordon bandwagon, and he always looked like something of a long-term project (albeit a higher end project), but I don't think it helps that he's a non-shooting tweener forward on a roster heavy on non-shooters and short on guys who can create scoring opportunities for others.