Depends on the discipline. Certain sports have an enormous advantage. Figure skating is basically dancing with blades. Gymnastics is pretty much the same. Athletes from those sports should win every time.
Football, basketball, baseball players, golfers, race car drivers etc. are athletes, but those don't translate well to dance.
Yes, being a football player doesn't prohibit someone from having the coordination for dance skills, but some of the worse dancers we've seen have also been football players. I can't recall one ice skater or gymnast who was clumsy on their feet like a lot of pro sport athletes were.
There's no doubt that ice skaters and gymnasts have a huge advantage going in.