Months ago, I read that the Anderson-Davis combo was terrible statistically so that might be factoring into their decision.
Asik would be a solid addition because of his strengths in the defensive department (an area young teams are prone to be weaker at). Barring serious injury issues, NO is a playoff team next year.
Anderson would be a good acquisition for the Rockets philosophical approach. If Howard can dominate opponents in the post, the open opportunities Harden, Anderson, and Parson will get will be terrific. Despite Smith's lack of outside shooting, his defense is superb and that is what Houston is going to need in those tight playoff games.