For a guy slated in the mid 20s to shut down his pre-draft process, the team is probably offering him a path to rotation minutes with a sold role in addition to a 1st-rd selection. It's probably a team like the Knicks or the Nuggets that are promising him the backup 5 role. The Knicks have two picks back-to-back in the mid 20s and are expecting to lose Hartenstein this summer in free agency. They could give Holmes a promise with one of the picks and be flexible with their other pick.
The Jazz could be giving him a promise, but it seems a bit early for them to tie up their late 1st and early 2nd, which could otherwise be packaged in another deal. Maybe they love him though.