First of all, be sure that he wants to get to the next level. I think most of us were athletes at one time, and we all got to the point to where we invested as much of ourselves into our training as we wanted and didn't go further. That's very much an individual choice. I think it's important as coaches that we don't project our expectations on our athletes without consideration of their expectations. That only leads to frustration for all.
If you are sure the athlete has the desire to get to the next level, be sure you are clear on their motivation for doing so. At a coaching clinic in Eugene during the 2008 Olympic trails either Terrance Mahon or Julie Henner were talking about how they had to approach training and racing plans uniquely for each athlete they were coaching. They specifically talked about how the 4 or 5 athletes were very different in what motivated them. One was all about time. One was all about place. One was all about "feeling". I can't remember some of the other motivations, but the idea was that the coach had to structure training activities and racing stategies according to what movitated each athlete.
Be sure that your goal of "Teaching your kids to RACE" isn't code for "getting kids to run like I expect them to". Understand your "thoroughbred's" motivations and develop his training and racing around them to the degree you can, and make sure the cues you use the day of the race to motivate/encourage him are aligned with his motiviations.
It's tough to do that with an entire high school team, but I do try to have successful upperclassmen share with the team what they do, and think about, in order to run well in big meets. It gives the younger kids a chance to see that different approaches can be successful and what techniques are used in each approach. This can provide the building blocks for their own approach to success. As a coach we can help them identify what's common in the approaches as well.