Cmon Strick. I shouldn't have to explain selection bias to you. HS early entrants are the cream of the crop. The top prospects.
Second of all, there aren't many who were drafted. That's true. But plenty weren't drafted at all. It is a huge failure of the system if a kid declares out of high school and isn't drafted. He forfeited his ability to earn a scholarship and get a college education.
Next, the players you mentioned have had good careers, but they'd also make like 3rd team all-HS entrant.
The last three years of the rule netted three All-Star or All-NBA players, Lebron, Howard, Jefferson, and Bynum in otherwise deep drafts.
I still haven't see the argument that KD was somehow harmed by going to Texas for a year or that the NBA would have been hurt if KG went to college for one year before jumping to the league.
I mean, that earlier period was pretty great, too. Kobe Bryant, Tracey McGrady, Kevin Garnett, Moses Malone, Amar'e Stoudemire, Tyson Chandler, Jermaine O'Neal, Rashard Lewis, and Al Harrington didn't go to college, either, and went on to have long and productive NBA careers while earning some of the lucrative contracts of their time.
1. There were not many high school who officially declared for the draft. Most McDonald's All-Americans, not to mention Top-100-caliber HS recruits, went to college during the preps-to-pros era. For as much as folks bemoan the inadequacy of the system, it actually worked really well for a majority of recruits and NCAA member institutions.
2a. You're welcome to compile a list of preps-to-pros prospects who actually declared for the draft and went undrafted. From memory, most preps-to-pros prospects were picked, even if they were picked in the second round. Second round and undrafted preps-to-pros players typically have and had long careers overseas where they were able to make money playing basketball. I'm not sure how many get or got a college education after retirement (if they ever intended to pursue college), but I would be interested in seeing those statistics.
2b. Players like Lenny Cooke are the exception to the rule. The proportion of picked prospects relative to declared prospects was higher for the preps-to-pros group vs. college freshmen, sophomores, and juniors, IIRC. Early entrants all lose their eligibility, too, and the odds of getting drafted decrease with age as a general rule.
2c. Not all players declare for the draft for purely basketball reasons. A lot of preps-to-pros players were not going to qualify and declared for the draft rather than going to prep school or the JuCo route. The calculus, then, has more to do with losing a year of development to high school basketball and being old for one's college year, which decreases the odds of getting drafted for the reasons stated above. That's even before you think about the lost income.
3. When a player loses their eligibility because they declare for the draft, it doesn't foreclose on their ability to get an education. It just means that they aren't eligible to play college sports.
4. Preps-to-pros was bad for college basketball because the NCAA and NCAA schools lost potential ad revenue made from having elite players on campus for a year. Preps-to-pros was bad for the NBA because many teams that drafted HS prospects either a) didn't scout them all that well (if at all) or b) didn't have the types of developmental culture in place to help them thrive.
Boys Among Men by Jonathan Abrams illustrates this reality really well. (This happens in college for new college students, too, fwiw.) The NBA had to protect it's brand and that's its right. I think the current organizational structure/culture of the NBA would be a lot better for preps-to-pros-caliber players, fwiw. I have no sympathy for the NCAA.
5. I used the players that I did because they prove my point. Even the non-elite preps-to-pros players have put together long careers in the NBA. Many of those that didn't (Martell Webster and Jonathan Bender come to mind) had careers derailed because of injury or issues that would have hindered their development and career prospects no matter what career path they chose (e.g., Eddy Curry, James Lang, etc.). Regardless, Amir Johnson having a 10+ year career in the NBA is pretty remarkable. I doubt he gets drafted if he qualifies at Louisville and plays four years.
6. Most NBA players were elite high school recruits. For as much as we debate about whether stars matter, HS recruiting analysts are remarkably good at predicting NBA-caliber talent. We can also bring up notable exceptions to the rule all day long (e.g., Stephen Curry), but it doesn't change the fact that even NBA deep bench players (e.g., Brandon Paul on the Spurs was a top-50 prospect in 2009) were elite HS recruits.
Finally, KD wasn't harmed, but I shouldn't have to explain why that's a bad example to you
. Schea Cotton is a better example. Plenty of top-25 players go to college and probably could have been drafted somewhere in the first round. Whether that is a good thing or a bad thing depends on how you view a few years in college vs. a guaranteed contract.
KD lost a year of his limited earning capacity as a basketball player by an arbitrary rule, when he otherwise would have been been paid well for that year, not to mention reached free agency a year earlier
This is true. The ultimate question is whether college is worth more than the alternative. For first round picks, I don't think that it is. I think that a guaranteed contract and the ability to track oneself into an NBA or professional career is worth more than playing for free and risking injury/lower draft position/falling out of draft contention. There is life beyond the NBA, too. International leagues can - and do - support lucrative careers for players who can't cut it in the NBA. A lot of the preps-to-pros cautionary tales (e.g., Ndudi Ebi) had productive and lucrative careers overseas.
One plan they are talking about is come out of HS get a 2 year/2 way contract with G League at the lower rate. Then go to NBA for the rest of your rookie deal.
If you don't do that, you'll have to stay in college for two years.
I'm a fan of a proposal like this, though I really would like to see how it plays out in practice. Most G-League success stories are older, more mature basketball players who were not scouted because of the league that they played in or were extremely late bloomers. I'm not 100% convinced of the developmental apparatus in the G-League, but I'm open minded.