This is Danny Ainge screwing over a conference rival (and chief eastern roadblock to the NBA finals) by giving a player leverage over the rival. Great GMing. It's not just about setting your team up, but its about hurting the other teams too.
Dunleavy has been really injury prone. If the Cavs are planning to give Dellavadova's, Williams, and Smith's minutes to Dunleavy, they will be disappointed. It's not like Irving doesn't have an injury history too.
This is just smart GMing. We don't have minutes for him. We don't have a need for him (especially with Green they are redundant). He doesn't really fit our team. However, if the Cavs have to dish out a 4 year, 50 million dollar deal, that would hurt their team for a long time.