Since we are having the discussion about assumed improvement over time and Jackson's performances to date, I thought it might be interesting to see A) how highly ranked players with subpar performances who left college after their first year have fared in the NBA, and b) how highly ranked players who stayed in college for more than one year have done in their following seasons.
I use BPM as a metric which is modeled to assess impact through the boxscore. It obviously has flaws but it's a solid starting point. Thus far this season, Jackson has a BPM of 0.0.
A) Top 15 Players based on RSCI, Declared for the Draft after 1st Year, BPM < 5.0, Entered between 2015 and 2020
Out of 17 players, only 2 have so far ended up being starting-level NBA players. 3 players can be declared NBA rotation players, and an additional 3 can be declared fringe rotation players. Some of them may end up being starters or out of the league down the road as it's still early in their careers for most of them. All of them with the exception of Ziaire Williams had a BPM of at least 2.5 and therefore considerably higher than Jackson's 0.0. 9 players are already out of the NBA, including 9 out of 11 players who entered college between 2015 and 2018 and declared after one year.
B) Top 20 Recruits (based on ESPN Ranking), Played Multiple Seasons in College, Entered between 2018 and 2021
It becomes very clear that improvement is not linear. In fact, many players hardly improve at all or even regress over time in terms of BPM, and those who improved usually did not have drastic jumps (if we take Miller: Jackson's BPM would have to jump 13.2 points (7.7 just for offense) to reach Miller's current BPM and nobody in that sample had a jump even remotely that big). The only (!) player out of 21 who genuinely struggled in his Freshman season, made steady progress and turned out to have a great college season later on – and is on track for a very solid NBA career – is Grimes (who switched the team and conference). Obviously we can look further back in time but I think it serves as a first illustration.
I realize that Jackson is younger than most Freshman but that alone cannot be an argument when there's so little historical precedent of someone seriously struggling in their Freshman season and then blowing up in the NBA (or even in college) later on. And even if we find more precedent once we look further back, the idea that his development is likely to be linear and drastic (as some seem to just assume) is just not borne out by history. So the argument needs to be a lot more elaborated than ‘he's so young, just wait and he'll turn into an elite player’ to convince me. If Jackson continues to have this kind of season and ends up being an NBA star down the road, that might truly be unprecedented in NBA history (or very close to it).
