Rim protection
The Suns rim protection has gotten a solid boost so far, but it still has a ways to go. Dunn is an immensely versatile and athletic defender who could get his fair share of blocks as a help defender. He averaged a whopping 2.3 blocks as a sophomore at Virginia, which is an insane number for a wing. Oso is just as gifted athletically, and averaged 1.3 blocks his senior season at Marquette.
Plumlee is a good, but not great, rim deterrent who will be an upgrade over Drew Eubanks. However, none of those players will be starting at center, which is where the current rim protection problem lies.
Jusuf Nurkić doesn't provide the Suns with anything in the way of defense, and given the additions of playmaking big men like Plumlee and Ighodaro, the Suns could be preparing to move on from him.
There aren't any legit starting centers on the minimum block, so this is one issue that would have to be addressed via trade. Attaching the 2031 pick to Nurk or someone else can land the Suns the defensive big they need.