One fascinating aspect of one-and-done has always been that, at least in theory, it has no logical basis for existence. Recall that the rule was instituted on July 29, 2005, in part, to give NBA franchises additional and badly needed information on draft prospects. There were to be no more Kwame Browns.

An understandable wish, surely, but one that affords an exceedingly odd occasion for a proscriptive rule. After all, in a world where high school graduates are immediately draft-eligible, why would you need to make this a rule in the first place? If a front office feels insufficiently confident to draft a player right out of high school, they can just pass. No one’s holding a gun to their head and saying they must draft an enigma.

If you’re more confident using a draft pick on a player who’s been in college for one season, fine, draft a freshman. Make one-and-done the “rule” for your franchise. It’s a free country.

Or so it would seem, based on how markets are supposed to work in a classical model. Then again, that’s not how professional basketball functions. Indeed, the NBA tried that very system 20-some years ago, and, eventually, found it wanting.

For the balance of the 1990s, teams did indeed pass, relatively speaking, on high school prospects, even though those players were draft-eligible at the time.

Number of college seasons played
NBA first-round picks, 1990-2000

Then a few straight-to-NBA stars like No. 5 pick Kevin Garnett, No. 9 pick Tracy McGrady, and, especially, No. 13 pick Kobe Bryant logged a few seasons and made it plain that drafting them would have been a pretty good idea.

Once this realization circulated throughout the league, the number of high school players selected in the first round began to climb.

NBA first-round picks, 1990-2006

The 2001 draft — featuring Brown, Tyson Chandler, and Eddy Curry at the top of the board (along with Pau Gasol) — tends to live in many observers’ memories, but it was 2004 that truly set a new standard. That was the year that a record eight high school players were picked in the first round: Dwight Howard, Shaun Livingston, Robert Swift, Sebastian Telfair, Al Jefferson, Josh Smith, J.R. Smith, and Dorell Wright.

The trend was halted right there, of course, and one-and-done was the result. Today, drafts and, especially, lotteries, are freshman-dominant. They have been, to varying degrees, for a decade.

NBA first-round picks, 1990-2017

But how much are we learning that we didn’t know before, exactly, from that one additional season?

                     RSCI 2016    Draft 2017
Josh Jackson             1            4
Harry Giles              2           20
Lonzo Ball               3            2
Jayson Tatum             4            3
Markelle Fultz           5            1
De'Aaron Fox             6            5
Jonathan Isaac           7            6
Bam Adebayo              8           14
Malik Monk               9           11
Miles Bridges           10          N/A

We don’t yet know the order in which the freshmen of 2017-18 will be selected, of course, but, by Jonathan Givony’s lights, we may be due for a similar evaluative echo next month on draft night.

                     RSCI 2017    Projection 2018
Marvin Bagley III        1               3
Michael Porter, Jr.      2               8
Deandre Ayton            3               1
Mohamed Bamba            4               5
Trevon Duval             5              45
Collin Sexton            6               9
Wendell Carter, Jr.      7               7
Mitchell Robinson        8              22
Jaren Jackson, Jr.       9               4
Kevin Knox              10              15

Yes, Duval stands out, and, sure, projected No. 6 pick Trae Young made very good use of the one additional year of evaluation afforded to NBA teams. The question then becomes whether one-and-done earns its evaluative keep simply by having flagged the fact that Duval “should” drop 40 spots and Young “should” jump 20.

That’s pretty much all the current eligibility requirement is accomplishing in terms of player evaluations. Otherwise, we could have held this draft a year ago, and it would have looked highly similar to what will (we think) transpire next month.

Actually, even that gives one-and-done too much evaluative credit. In an alternate reality where players could be drafted straight out of high school, it’s possible Duval would have been a 2017 pick — but Young, surely, would have gone undrafted. Then, after the amazing freshman season that we now know happened, Young would have been a 2018 lottery pick. In this scenario, then, the evaluative function of one-and-done with regard to the top of the board is to prevent Duval from having been a high draft pick a year ago, period.

Needless to say, we don’t know if this verdict on Duval will be affirmed by the future as correct, it’s just how it looks in mid-2018. That’s the point. There is no apodictic Archimedean point in time at which we say, “Aha! Perfect information on these now transparent and unchanging players. Let’s draft!” One-and-done changes the picture, typically very slightly, from what it would have been one year earlier, but the same picture with regard to any group of players will also be changed very slightly one year after that. Ask Markelle Fultz.

From the inception of one-and-done and even before, high-lottery-level NBA prospects have been most often identified before they get to college. Victor Oladipo is one spectacular exception to that rule, of course, and there are others. But Oladipo got to where he is despite being adjudged as unworthy of drafting immediately following his freshman season. That road to the NBA is always going to be open, regardless of which eligibility rule is adopted by the league.

What we’re talking about additionally are players that have already been identified as lottery material before they’ve played a single college game. The label hung on these players is turning out to be correct, or at least believed on draft night, in the vast majority of cases.

Meaning the freshman season required by one-and-done tends to function less as a rich evaluative period than as a pass-fail last hurdle to be cleared. If the former were the case, we’d expect to see at least an occasional case of dramatic upward mobility, up to and including, say, a player from outside the top 100 entirely being drafted after his freshman season.

We don’t see that. Marquese Chriss jumped from the No. 52-ranked prospect out of high school in 2015 to the No. 8 pick in the 2016 draft. That’s the best Cinderella story we have for freshmen in the one-and-done era. One-and-done isn’t adding dispositive information at the top of the board on a Fultz or a Ben Simmons or a Deandre Ayton as much as it’s sorting out and tripping up the occasional Cliff Alexander or Chris Walker or, who knows, Duval.

In fact, it’s conceivable that what one-and-done has done more than anything else is simply affirm, structurally, that college freshmen form the population of interest at the top of the draft board. There was no such single agreed-upon population for 15 years following the eclipse of college seniors in the early 1990s. Maybe there’s value to the NBA in marking out the fishing hole so plainly, but, with the confidence of 11 mostly unsurprising one-and-done drafts now in our collective memory banks, it seems likely that high school seniors could henceforth serve as that population of interest.

To be sure, there’s a good deal of entertainment and dramaturgical value in seeing sure-thing lottery picks go up against scrappy and emboldened opponents who will never sniff the NBA in a win-or-go-home setting each March. (Personally, that’s one of my favorite parts of the NCAA tournament.) And, though an entire generation has now ascended to top jobs with no working memory of any other way of doing things, one-and-done gives college coaches the inestimable comfort of knowing that they’re recruiting against other college coaches and not against the NBA.

Those are tangible benefits, certainly, but it’s far less clear that new player-evaluation information is included among the advantages being delivered by one-and-done. If, other things being equal, the optimal moment for draft eligibility is the point at which an evaluative consensus has been forged with regard to the players in question, then that line is currently being drawn one year too late.