Roboto is very catchy. No doubt about it. You can't argue that. One of the reasons it became their second biggest single and would have hit #1 had one Michael Jackson not been in the way....
Roboto was the biggest of the #3 peaked singles. Styx singles that peaked at #3 were Roboto, Best of Times, and Show Me The Way.
If I remember correctly, Keep on Loving You kept it from going to #2 or #1. I always felt it was by far their best ballad.
What is far more mystifying to me is that Don't Let It End peaked higher than Journey's Faithfully when they were released at the same time. IMO Faithfully is 100X's a better song.
I also felt that Desert Moon was going to land at least in the top 10.