I have to disagree with this somewhat.
While training, supervision, and environment/culture certainly has strong bearing, the quality of the hires is very important.
Herb Kellerher, the founder of Southwest Airlines, in his book addressed that, saying he recruited new hires after thoroughly evaluating their personalities, rather than their previous experience, as he believed you could teach most applicants for service positions the job from scratch, but you couldn’t really teach good personalities…