Devin Booker is a superstar in the NBA. Superstars are often required to carry their teams when the non-superstar players struggle. Unfortunately, Devin Booker has to carry this Suns team every night, every minute he's on the floor, if the Suns want any chance to stay competitive. That's an unfair ask, even for one of the most talented players in basketball.
In short; without a superhuman effort from Book every night, this team doesn't stand a chance. It's a harsh truth that Booker is learning firsthand, and Tuesday's game against the Warriors perfectly demonstrated the bleakness of the situation.