As impressive as this kid is, and he sure sounds like a great HS runner, surely the shoes probably are worth almost what the wind took away. So in the new shoes he might run well under 4 but it sounds as if sub 4 is going to be done perhaps 5-10 times per year by high school kids with the new shoes.
Professional 1500m times have not improved. Neither have 5000m times for that matter.
Times have improved at the levels where there hasn't been rampant PED use before. The super shoes have a big effect, but most likely not as big as chemical PEDs. All other things being equal, circa 2000 shoes + EPO is a better than the super shoes, but the super shoes are significantly changing what is a "great" time in US high school and college, even in the mile. And don't try the "PED use has always been rampant among 4:15 milers in high school", that's just silly.
My son raced today and said he couldn't feel the wind at all on the track. The stadium protects it.
The wind has been coming and going. Your son ran at a time with no wind, others ran at a time with wind. The stadium doesn't fully stop the wind. There are times when the flags on the field are waving a lot.