One of the odd things about the Suns since "the trade" has been that they have gone with only four guards (they sent Penny and Stephon while receiving Eisley). Marion is not well suited to playing guard plus Zarko has struggled. With Eisley playing badly and the injured, it meant the Suns had only three guards so JJ played almost all the time.
If they add Vujanic and a FA guard without moving Eisley, they will end up with six guards. Hopefully they will be able to give JJ a break once in a while.