"Kids are all different. I used to treat 1-15 (on a roster) exactly alike. That’s how I was taught" by his mentor, former North Carolina coach Dean Smith. "That way, nobody knew who my favorite was. The important thing is to get each of them better."
This can be a major issue in coaching any sport, including distance running. Far too many coaches, perhaps enamored with the system they have devised, insist on coaching everyone to a single standard rather than fitting the system and the standard precisely to each individual. With enough good recruits, they might get 4-7 runners (in >>-cc->) to reap benefits out of the system, yet that may be out of a roster of 10-20. They can lead great performances in championship meets while having a poor success rate in terms of developing improvement in all of their athletes. This happens on the post-collegiate level, as well. A coach might work well and arrive at notable results with one or two athletes yet when looking at that coach's entire body of work it could be revealed that he has led fewer than a quarter of the athletes with which he has worked to significant improvement. This is what separates a coach like Lydiard, who made champions out of runners who happened to live nearby him. I have recognized similar abilities in coaches like Mark Wetmore (revered for turning walk-ons into all-Americans) and Scott Simmons (took Queens University from having never qualified for cc nationals to 15th place in his first season there and 7th place in his second (and most recent) season there - largely with runners who were already there when he had arrived - and qualified QU's first female runner to nationals this past season, as well), who seem to make much out of seemingly little.