Have they?
Keyonte is 1½ years and 100+ games in and still doesn't play D and is one of the worst players on D in the league. How is priorizing Keyonte's PG play (a position he will not play in the NBA) over playing D a good call? If Keyonte is on a future Jazz team (and if he's to stay in the NBA) they need him to play D, not to play PG.
Sensabaugh spent almost all of last year in the G league or on the bench, because Hardy couldn't get him to understand that he needs to focus on everything else but scoring. Granted, now he's been very good for the last month. One month doesn't do it for me though as proof of great development.
Collier was one of the worst NBA rotation players getting steady playing time until about 3 weeks ago. And yes, he's been good and shown promise for those 3 weeks, but again: that's three weeks.
Williams hasn't shown any signs of development this season - he's exactly the same non-entity as in game 1.
Hendricks had some ok games at the end of the year, in mostly garbage games playing with G-leaguers. His 3 games this season were not good. Hendricks had the skills and capability on D already the day he stepped into the Jazz facility. Refining those is of course important, but he has to have some role on offense, and that's completely unproven so far.
Flip? Ochai? NAW? THT? No development while with the Jazz really.