Several things worth remembering. A) Salazar is mostly coaching athletes who were already proven winners before they got to him; B) It's not easy to take fast people and make them faster; C) When you're near the top, it's more likely that you fall short of your goals than attain them.
Rupp is a clear exception to A) above, as Salazar did develop him.
Overall, I'd have to give Salazar very high marks. He's obviously devoted to his athletes, and vice versa. That's about 99 percent of the equation.
By contrast, the Hansons work with much less talented athletes, and have some successes, some less than great successes (like all coaches, ie, Mahon, McMillan.) In present setups, Hanson athletes will never match Salazar athletes. Which doesn't make Hanson program a failure. Just different than Nike-Salazar/Schumacher, etc.
I'm not optimistic about American distance runners vs the (East African) World, but if I were a young 27:50 American guy, I'd beg to get into the Salazar program. What other approach would offer me a better chance?