Aging Curves for Big Men; Do they take longer to Develop?


Today, the series of 2-year APM-based Aging Curves moves onto “Big Men” and offers an answer to the question, “Do Big Men take longer to develop?”; the response may be counter-intuitive.  The article also addresses the relative value of big men compared to their “Guard” and “Wing” counterparts, ultimately concluding that veteran Big Men make the largest positive impact on the scoreboard.  The same ground rules apply as in previous articles, and “Big Men” are defined as Power Forwards and Centers as per basketball-reference.

Big Men Aging Curve Results

The first two graphs include every player classified as a power forward or center by bball-ref in any given season of the gotbuckets APM sets.  The first graph reflects the minute-weighted development curve on Offense for the entire group, while the adjacent table provides the 2-year APM and number of players represented for each age.  Two conclusions jump out.  One is that these guys are poor at offense.  Even at their pinnacle, the cumulative “Big Men” do not approach 2-year APM of zero.

The second conclusion is that the Big Men peak very early on offense, with the best seasons occurring at age 21 and 22 and the best fit curve peaking around 24.

Big Men Offense Aging Curve

Below, the curve for the Defense split of 2-year APM is shown, along with a table featuring combined 2-year APM.  The best fit curve includes a highly positive trajectory, peaking in the early 30’s at over 2.5 pp100p.  The defensive contributions greatly outweigh the offensive struggles, resulting in total 2-year APM summing above zero for nearly every season from 23 until 35.

Big Men Defense Aging Curve

Next, as with the prior articles, a few “control” samples are checked for uniform subsets of “Big Men”.  The graphs below feature two groups.  The first two graphs include only the Big Men that qualified for 2-year APM (played 750 or more minutes) for each of age 21 to 26 within the 2003 to 2013 2-year APM sets; there were 30 players in this group.  For the graphs of subsets of players, guys that shifted between small forward and power forward (think Shawn Marion, Andrei Kirilenko, etc) are generally excluded, as they were “Wings”.

Big Men Offense 21 to 26

Big Men Defense 21 to 26

These graphs generally mimic the results for all “Big Men”, except the offensive peak occurs even earlier, at age 21.  Specifically from this group, there were role players that went from decent to abysmal on offense (Andris Biedrins, Eddy Curry) or strong to average (Charlie Villanueva).  Star performers on offense like Chris Bosh, Dwight Howard and Paul Millsap showed stagnant growth, or even slight regression across this timeframe.

On defense, steady improvement was exhibited, with Dwight Howard, Andrew Bogut and Josh Smith becoming huge bucket-stoppers. A relatively fascinating item is that no other group showed results that trended as well as Big Men on defense.  The curves for all three graphs are steady and relatively predictable, with R^2 between 0.8 and 0.9.

Next, the Big Men that qualified for 2-year APM for each of age 26 to 31 within the 2003 to 2013 timeframe are investigated; there are 37 players in this sample.  Of those guys, again this subset reinforces the results of the original graphs.  Offense perpetually declines, but defensive performance climbs at a rate much faster than the offensive skid.  By age 30 and 31, based on combined 2-year APM, this group is reaching their peak years, thanks solely to the large defensive improvements.

Big Men Offense 26 to 31

Big Men Defense 26 to 31

Comparison to Guards and Wings

The “Big Men” diverge greatly from the results of their smaller counterparts.  The 2-year APM Aging curves on offense for “Guards” and “Wings” were above zero for their entire careers, while the “Big Men” never even approach that threshold.  Using their general superiority in ball handling, passing and shooting, the smaller players can create offense inside and out, for themselves and teammates.

At the other end of the court though, from age 20 through 31, the “Big Men” defense curve, starting at an already respectable level of positive 0.7 pp100p, increases by nearly 1.9 points per 100 possessions.  Compared to the Big Men Offense Curve, or either offense or defense curve for Guards or Wings, no other aging curve looks like the Big Men Defense Curve; the second biggest improvement through a career is Wing defense, which improved only 1.3 pp100p over the course of players’ careers.

So, Big Men do take Longer to Develop?

An adage frequently heard in the NBA about young Bigs is that patience is warranted, because they take longer to develop.  That does in fact appear to be true, evidenced by the table below.  The veteran big men began their careers with similar production as guards and wings, but by their primes are clearly the most impactful players on the court thanks to their defensive dominance.

Combined 2year APM by POS and AGe

On the other hand, I don’t think this outcome reinforces the narratives that pundits and analysts perpetuate.  Most of the time, the explanation is that young bigs struggle to compete offensively, as they initially fumble passes near the basket, and dribble the ball off their feet on a post move.  The common insight is that this will improve over time, because that is what Big Men do.  Contrary to that though, the collective offensive impact of Big Men does not improve. The offensively challenged young forward or center tends to not improve beyond his early bucket-generating abilities, but in learning how to best use his size for defensive advantage, he can become a focal point of team success.

(Author’s note:  The rest of this article is hypothesizing.  When seeing a result, I ask “why?”  The discussion below is a non-quantitative attempt at that.  A really instructive take on the results above would come from a coach who has worked with players at all levels.  I am not that.  If you have thoughts on the results above, let me know in the comment section.  I am interested to hear cool ideas.)

These discrepancies seem reasonable.  On offense, smaller players control the ball.  In the pick and roll, they utilize their full range of skills: ball handling; passing; shooting; and decision making.  Each of these are skills they can improve as time goes by, but possibly more than anything else, their decision making has great room for improvement.  In high school, AAU and collegiate play, these Guards and Wings spend a lot of time honing their ball handling, passing and shooting.  These are the skills they have been practicing since grade school, and the ability to improve greatly after age 22 or 23 may be limited.  Surely as they play in the NBA they will add a few new wrinkles, but these traits are what brought them to The League; most are already very good at these skills, and it makes sense that the average offense split of APM is decent from early ages in a “Guard” or “Wing”.  Their approach to the offense, and potentially the pick & roll in particular, is a place where much growth is available, hence the increasing offensive contributions throughout their careers.  Once entering the NBA, the young Guards and Wings experience way more pick & roll action than they did in earlier competition.  And as they gain this experience, they become more capable of utilizing their skills toward their advantage in the pick & roll.  When is the right opportunity to shoot?  To pass?  To drive?  What about the appropriate timing to use the Big’s screen, or finding him afterwards?  Long story short, there are many intricacies in how a Guard engages the approaching pick and how the defense has responded.  Learning the most effective action through experiencing these permutations, there is a lot of room for growth for the young, ball-dominant player.

On defense, the inverse is true.  The Big Men dominate the approach to impeding the other team, including the pick & roll.  Obviously, the guard needs to anticipate the pick and fight around it, but there is only so much growth that can be done there.  Perhaps that is why the defensive aging curve for Guards didn’t form a strong upward trend.  For the Bigs though, mastery of taking the best angle to contain and obstruct the guard, while also minimizing passing lanes to the rolling big, and learning the tendencies of various players, takes experience to master.  Whether an “on-ball” or “help” big, solid rotations and recovery will greatly define the defense’s effectiveness.  These are all skills that are just as likely to be aided by learned experience instead of being primarily a function of innate size or athleticism.

On offense, the NBA skill sets of Big Men are fairly similar to what they have worked on for the previous ten years of their lives.  A post game, setting a pick, hitting a jump shot; like guards with their dribbling and shooting, these are areas where a few new wrinkles can be added, but to some extent they have been working on these skills their entire lives, and if they haven’t shown a prevalence towards mastering those by age 22-ish, it is not likely to happen.  Some Big Man offensive skills, like offensive rebounding or finishing over people in traffic, may be skills better served to the energy, athleticism, and fresh knees of youth.  The explanation for the negative slope of the Big Men offense Aging Curve could also be that as they get older, Big Men are asked to contribute more on offense.  Unfortunately, the plays they use: low post moves; isolations from the wing or high post; mid-range jumpers; are not the most efficient play types, and in effect take the place of more efficient types of offense.  While just hypothesizing, that could explain the non-existent growth of the offense split of 2-year APM for Big Men.

In summary, Big Men do take longer to develop.  It’s just not in the way that people typically mean it.  Blessed with the gift of size, bigs learn how to use that mass to their advantage, whereas there appears to be an offensive skill threshhold that they meet early.  As they finally learn how to play defense in the NBA, more and more value is extracted from having the mammoth men on the court.


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