I tried looking for my diminutive Mavericks guard JJ Barea, but I can't find him on the wavier wire. Does the search not work?
The reason he is not yet available is that he is a Restricted Free Agent.
If he goes unselected in the 16th round, he will immediately become available. (Restricted Free Agents have four or less seasons of NBA experience. They cannot be picked off the waiver wire until after all 16 rounds of drafting have been completed.)