Hasay is a victim of a system flaw that plagues most young prodigies. They simply are not put on a path to get to the next level - let me explain what I mean:
Many young prodigies are gifted athletes with good natural mechanics, body types and strong natural VO2 Max characteristics. So they naturally show good promise early in running and so are placed into the youth running system in this country (Jr Olympics, middle and high school XC and track). This system emphasizes VO2 Max and speed development, as all "distance" races they are allowed to compete in are VO2 Max and speed cenetered (800-5k). These prodigies, given their natural talents, quickly develop their speed and VO2 Max (which can be developed to close to maximum in just a few years), and soon become youth phenoms at races of this distance. But soon they reach close to their VO2 Max and speed maximums and stagnate.
In order to them to continue to improve and reach the world class level as an open competitor they must have the aerobic and thershold development along with the VO2 Max and speed development. But unfortunately they have done little in the first 8 yrs of their running careers to develop that to a high level (becaus eit was not as immediately necessary to see good initial gains). Because they produce well early off of a lower mileage and higher speed based system (because of their natural talents) they are often coached in a manner that does not allow them to do enough mileage and distance and threshold work needed to develop aerobically to a world class level, and aerobic development (capillary development, lactate threshold development, aerobic threshold development) is something that takes far longer than VO2 Max and speed to develop to a world class level. Many youth coaches and school coaches mistakingly believeing they that because of these kids run fast off of lower mileage that higher mileage and significant threshold work isn't necessary for them or the coach personally lack the frame of reference (because of the system itself in this country) to realize what world class aerobic development is. Or even more probably they work on what gives them the most immediate benefit (early on this is speed and VO2 max) and allows them to immediately be successful instead of looking at what the long terms needs of continued development is.
So many young prodigies, like Hasay, get to a point of stagnation, and find it hard to get to the next level (world class open competitor), simply because they are not there in terms of aerobic development. They go through a system that believes 40-50 miles a week in high school is high mileage and that 60-70 miles per week in college is high mileage and more than sufficient. And often this simply puts them well behind most world class runners in terms of aerobic development. Unfortantely by the time some of these athletes and their coaches realize this (if they do at all) they are very far behind the curve and starting late on what takes the longest to develop.
Many people see a Jordan Hasay type who runs very well at 1500 and 3000 as a high schooler and believe that in 4 more years they will make incredible improvements, but if the got there based mainly on VO2 max development with little aerobic development, the chances are they will only improve slightly to modestly, as Hasay has done.
In order for these distance phenoms to make it to a world class level (in todays competitive world) they must have a complete package (aerobic development, threshod development, speed development, VO2 max development) and since threshold and aerobic development are the areas that take the longest to develop to a world class level they should be begun early and worked on significantly through the runners career.
None of this is necessary the fault fo the athletes or even many of their coaches, but simply a system that is not set-up to develop many runners to a world class level.
Arthur Lydiard pointed this out to us in an open letter to U.S. Coaches back in the mid 1990's. Unfortunately the advice he gave has largely been ignored or poorly disseminated.