I'm not surprised at this data. I've seen the same thing all the way down to 8-year-old travel teams in basketball and soccer.
I would be interested to see another graph showing the Division I coaching carousel. I bet the trend lines might be similar.
I am betting trend lines in D1 coaching will reflect the amount of money thrown at programs and salaries in the last 15 years. Fanbases with unreal expectations and "what have you done lately" mentalities fueling the arms race have . IMHO. been the catalyst for college coaches on the carousel and are independent of the numbers of kids from Grade School on into the Pros (My baby gonna be the next Michael Jordan) listening to parents who way overvalue the skillsets of their children.
I would love to see the research on the increase in volatility of coaching positions in HS, college and the NBA ....I am thinking that the run up of "FANS" and the increase in money/arms race/facilites and need for interest/donations has fueled the Coaching situation. When I talk to aspiring young men I tell them NEVER to go to a school to play for a coach. THis is what I tell them.
" YOu will be going to get an education, you will be going to a place that has a wealth of resources and if you use them you will be set for life beyond basketball, I will repeat what I heard a great coach say to a kid who was waiting for a B10 ride ...."son you have a Butler offer in hand,,,,when your shot is not falling, when your coach...and quite possibly not the coach who recruited you is on your case, your girlfriend is dumping you and you just got home from a late bus ride and have to get up for an 8 oclock class that you are having a hard time with you need to be in a place where you are going to wake up , look around and be very happy that you are there" Those were words that are true. YOu can't go to IU if you want an engineering degree, take the PU ride....school has to fit. YOu are not going to be happy if you are recruited over for your postion....school has to fit. YOu are not going to be happy if you can't adjust to an urban or rural campus, school has to fit. NO matter what you do with basketball the school has to fit....that is who is giving you the ride.....not the coach"
That said.....As a result of the coaching changes and the facilities races ..........., I *DO* think what an athlete and his parents sees as his future has lead to putting kids on a path to take advantage of the riches the basketball world has in store for them indirectly leading to this situation.