@Who hinted at it, but their frontcourt play is just very subpar. Nurkic was limited, and while Nick Richards isn't terrible he's J.A.G (just a guy) IMO. There's a lot of games where the Suns simply get outhustled and outrebounded inside. Durant, Booker, etc. just aren't always going to make up for the lack of rebounding either. Beal has also been inconsistent and often unavailable too, which I know frustrates Phoenix fans because there are games he misses because of a "toe" or "finger" injury, like really dude? If Beal played like a consistent 3rd option I think they could be much better but he doesn't. I actually think Durant and Booker have been great this season and put in the effort. But Booker is a bit limited on defense.