2. No Plan B at the point guard position
If there is one player who is not going to receive any criticism for the Suns' current troubles, it is Booker. Alongside Durant, he has done everything he possibly can to help this team win games. It is not his fault he has missed some time through injury, and when he is on the court, you could make the case Booker is playing the most complete basketball of his career.
He has taken the responsibility of being the Suns' lead ball-handler extremely well too, and so far has averaged 8.2 assists per game. By far the best number he has ever managed (career average of 4.9), and a top 10 mark in the league today. The drawbacks of having a scorer as incredible as Booker were pointed out before the season, and they are still fair problems to point out through 27 games.
When Booker is injured, the Suns kind of have a "point guard by committee" approach to creating plays. Which might empower some players to make more decisions which is great for them personally, but against the elite point guards in the league today, is also going to explain why the Suns struggle to win games consistently.
If that doesn't work, then often the ball is just given to Durant to try and make something happen. Which he often does, but at this stage Durant should be viewed as a late game closer and the one who the Suns lean on late. Not midway through the first-quarter of a game against the Trail Blazers (he had a game high 40 points), and that was a game Booker also played in.
In order to reach their full potential, the Suns need to have periods where Booker comes off the ball again. This will free him up to be the scorer we all know that he is, while it will also mean they have a Plan B in the form of a player who is used to running the team. Theo Maledon was recently signed to a two-way deal, but they are going to need to do more than that to remedy the point guard situation.