I am not saying that everyone does these, but I have seen a lot of bad teams around me and I think I can attribute most of them to one of these things.
1. Not enough miles - Not sure why some coaches don't give their athletes more than 2-4 miles per day, unless they just don't understand training.
2. No Tempos - Afraid to dish these out because they might be too hard or someone might fail.
3. Too many hard workouts - They just have to get at least two or three hard workouts in per week even if there is a race. Even if they have to do them back to back.
4. No long runs - You have to find a spot to get in a long run at least once and a while. Not saying it has to be every week but you need to find a spot. Should build up to triple the race distance.
5. Train through races. I get it every once and a while but kids need to learn how to race and if they never get to know be at their best and race all out then how do they learn?
6. Not enough races. Now some teams have gone the completely other way and think that their HS team is a college team and don't give them enough opportunities to learn how to be a better racer.
7. Structures off season training. Not having something going in the offseason is a death sentence and you might as well give up as a coach because you can't fix it.
What else am I missing?