There was a brief stretch there, in the middle of January, where Trey Lyles was getting some decent minutes and actually putting up decent games with them. The rest of the year has been him getting decent minutes and doing very little with them, or, more recently, getting very few minutes and and doing very little with them.
His reduction in playing time is because the Jazz are in what’s known as a “playoff push” and it means that not-as-good players like Trey have to take a back seat to better players, like Shelvin Mack. There is simply not as much time to devote to developing an unpolished rookie when chasing the 8th seed to earn the privilege of getting swept by the Warriors.