Guest Post: Age and upside in the NBA Draft

Freelance Friday (Thursday, in this case) is a regular series on Nylon Calculus where we accept submissions from around the internet to bring the broadest possible range of content and to provide opportunities for new voices in basketball analytics to be heard.

Today’s piece, from Saurabh Rane, discusses the expected value from each pick slot in the NBA Draft. Saurabh is a Bay Area native and longtime Warriors fan with an unhealthy obsession with numbers and sports. Follow him on @SaurabhOnTap, where he pretends to be a NBA coach or on his blog, Saurabh.R.

Have a question, comment or submission for Freelance Friday? Contact us via email at TheNylonCalculus at Gmail dot com or on twitter @NylonCalculus 

In the weeks leading up the 2016 draft, fans and teams alike try to project the career arcs of more than a 150 NBA hopefuls. Many mock drafts and scouting reports have been littered with the term “upside”, which analysts typically treat as a direct function of age. Simply put, the premise is a younger player has more upside than an older player. For example, 19-year old freshman Jamal Murray versus 22-year old senior Buddy Hield debate is a perfect representation of that kind of analysis.

Kenyon Martin was the last college senior to be taken with the No. 1 overall pick, and since then NBA teams have made an emphasis on drafting younger players. The below chart illustrates how teams have begun to draft more players under 22[1. It is important to note there is a bit of a feedback loop – teams start to draft younger players higher and consequently, better prospects start declaring earlier.]

Image 1 LotteryAgeFreqEra

The flipside side of drafting younger players is the term that’s heard as the opposite of “upside” – “NBA ready”. Analysts typically save that term for older prospects. However, recently age has not corresponded to any measure of being NBA ready. Thomas Robinson, the 6-9, 237 pound, 21-year old junior out of Kansas was touted as a prototypical NBA ready prospect, but ultimately failed to make an All-Rookie team. Conversely, Devin Booker and Kristaps Porzingis, 19 and 20 years old at the time of the draft, were largely considered to be long-term prospects and ended up making All-Rookie First Team.

In this analysis, I’ll be taking a look at how age drafted corresponds to how NBA-ready player is, as well as their upside. Additionally, I’ll be looking at when players have their best seasons, as a function of age drafted.

Methodology

Player value will be determined by their peak VORP (Value Over Replacement), similar to how it was done in my last piece, Expected Value in the NBA Draft. A player’s season will be deemed eligible for this analysis if they play 10+ minutes per game and 40+ games; player seasons that did not meet that criteria will not be included.

Only drafts from 1984-2010 will be looked at.

How does age at draft correlate to upside?

Below shows the first eligible season (defined by first season with 10+ MPG, 40+ GP) versus age at draft time[2 .In charts that do not use “Pick Range” the “23+” category will be split into”23” and “24+”. 23+ was used in these charts since small-sample size was an issue in the top 6 range (only 6 players age 24+ have been drafted in the top 6 since 1984)]. On a more macro-level, the data seems to suggest that there is little to no correlation between the age of the time of the draft, and how well players perform when given play time[3.By including only seasons where players have played 10+ MPG & 40+ GP, the data overvalues players that take a few years to break into the team’s rotation. For example, Avery Bradley did not break into the Celtics rotation until year two, consequently year two is considered his first eligible season.]. Worth noting that 18-19 year olds picked high in the draft initially struggle as compared to other older players in the same range. That advantage disappears further along the draft.

Image 2 PickRangeFirstEligible

The below chart shows the opposite of the previous chart – upside. Age seems to play a bigger role in upside, regardless of draft position. This suggests that there may be some merit to the notion younger players have more upside than their older counterparts in a draft.

Image 3 PickRangePeakVORP

When do players peak?

The importance of age versus seasons played when projecting player development potential is another frequently debated topic. For example, C.J. McCollum, despite being 24-years old is entering his fourth season, and second year as a rotation player. Kyrie Irving, age 23, is entering his sixth season and has been a major part of the rotation for all five years of his career. It’s certainly reasonable to expect that McCollum will make larger strides as a player moving forward than Kyrie Irving[4. This is projecting how much each player will improve moving forward; it is not a statement on each players current ability].

The chart below illustrates when players picked in the lottery tend to have their best year in terms of seasons in the NBA and in age. Most players that were not drafted at 18-19 years old tend to peak right around the 4-5 season mark, while younger players hit their peak around 6-7 into the league.

Image 4 PlayerPeakSeasonAgeDraftedLottery

The below chart, looking at the player age during their best season seems to correspond to the previous chart. If a 21-year old draftee is expected to have their best season 4-5 seasons in the league, it makes sense that the below chart shows a 21 year-old draftee’s best season at around age 25.

Image 5 PlayerPeakSeasonAgeDraftedAlt

However, note that the above charts are averages of all NBA players. As shown in the chart below players that peak as rotation players/starters will do so 3-4 years into the league, while All-Stars/All-NBA players do so 5-6 years into the league. Obviously, the difficulty for teams lies in projecting which players will develop into All-Stars. If a given prospect is to develop into an All-Star, teams can reasonably expect that to happen ~5 years into their career.

Image 6 PlayerPeakSeasonPlayerRoleLottery

In conclusion, age does seem to have a large impact on a players upside, as seen in the first section that younger players tended to become better NBA players than their older counterparts drafted around the same pick.

Additionally, the idea of a player’s prime beginning in their late 20s may be a flawed premise. Historically, players have had their best individual season an average of five seasons into the league. The premise of players entering their prime in their late 20s was likely developed in the late 80s and early 90s where the average age of drafted players was higher than it is in the modern era. In the current NBA I would expect role players/starters players to enter their prime at an average of around age 24, and stars/superstars to do so around age 26.


 

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