As spring comes, teams start choosing between playing for the postseason and playing for offseason. It becomes interesting for NBA fans to see when teams make the flip.
The concept of weighted age is not a new concept but it is one way to track the timing of that flip. Weighted game age (WGA) is essentially taking the age of the players but accounting for the minutes they play and then dividing by the sum of minutes played, in this case, specifically for that game. (Note: I just used current ages from stats.nba.com so this doesn’t account for birthdays or age in days.)
Due to blowouts or one-game oddities, I used a 10 game moving average to smooth out the game-to-game WGA trends. I took a few static cuts of this data to highlight some trends. Below are the teams who made a midseason resolution to get younger and committed in spades:
What’s the common thread? They ALL wear purple (the correlation game is crazyyy). Equally synchronized as their uniform colors is when these three teams decided to make the rebuild pivot and to start playing youngsters. We could probably identify the exact game it happened for each team.
The difference for the three is stark: Sacramento went from one of the older WGA clubs to being average-aged while LA and Phoenix are probably the most “millennial” teams in the league now. Here are your contenders:
It’s been fairly steady for this group, although the Spurs and Warriors have battled some injuries. You can see exactly when they called on their younger reserves. For the most part, it’s clear the elite teams stick with their rotations and as a result, their WGAs are very close to where they started the season. Now, rebuilding clubs actually offer some of the highest standard deviations of WGA but here are some other oddities:
Memphis is wild. It’s actually quite rare to get significantly older as the season progresses but yeah, they did it. Dallas is also quite unusual. You can see when they moved away from Deron Williams and Andrew Bogut but yet they still look middle-aged. In fact, Dallas has gotten a lot younger with Seth Curry and Yogi Ferrell in the starting lineup, but the presence or absence of a 38-year old Dirk is a heavy weight on the scale.
Brooklyn is on the chart for being relatively steady despite being a cellar-dweller. That’s because, unlike their fellow win-challenged teams, they don’t wear purple and they don’t own the rights to their lotto pick, so they didn’t need to make the hard pivot at the trade deadline. Still, Brooklyn’s WGA is creeping down. By comparison, Chicago is interesting because it has been playing for the playoffs on the surface but it has gotten younger faster than Brooklyn has, with moves like trading Taj Gibson and feeding Bobby Portis minutes.
This is the line chart for all teams (a former coworker of mine referred to these sort of charts as “rainbow mountains”) highlighted as a gif. You can also play around with it yourself here.
Next: Nylon Calculus -- Elite scorers vs. elite defenses
In conclusion, WGA is provides a simplistic but fairly accurate purview into when and how much teams have committed to developing their young players (and acquiring ping pong balls). It also highlights how consistent the true contenders are despite the ups and downs in the season.