So on my team, many of the guys do barely any summer mileage. They run about 3 days a week, which is IMO very minimal for improvement.
Last summer (going into 10th grade): 25-30 mpw per week, ran 5-6 days/week for 12 weeks
You would have expected I would have been one of the lead runners on the team... nope.
I peaked mid-season and ran worse during the season's end (no injuries), while nearly everyone else set PRs at the final meet.
I know I did the work, so only thing I can think of is my genetic capabilities. Considering none in my family were good at sports, was I already screwed before I even began running?