I think Horford is clearly more important than Smart, but taking salaries into account and who might be the replacement for Horford, I don't think triboy is so far off. Whether you like Smart or not, he obviously has an impact on our defensive unit as a whole.
There was a poll a few weeks ago about who we thought was the best defensive player on the Cs. At the time, I felt the answer was Horford, but I would like to change my answer to Smart. Positional defense is important, but the way Smart plays defense is uplifting to the whole team.
I have enjoyed watching Horford play and I still want to see him play with Hayward, but I will survive if he is included in a deal for Davis.