Or they just think there is very little difference between Irving and Knight. You generally value bigs much higher. They'll still probably get one of the top-2 PG's. Only risk would be Irving goes #2 and then the JAzz take Knight, That would leave them with Kanter/Williams. That's not a bad scenario. Take Irving and then the draft could go (as expected) Williams #2 and Kanter #3, leaving Knight as the BPA at #4, but the Cavs would have already selected Irving.
So is Kanter/Williams or Kanter/Knight better than Irving/Vesely (or Valanciunas)? If I were the Cavs GM and Irving didn't completely blow me away in workouts, I might consider taking Kanter #1 (and I'm not a huge fan of Enes).