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September 6, 2011

The Age of the NBA

Filed under: Uncategorized — Kevin Pelton @ 12:17 pm

Friend of this site Tom Ziller has a thought-provoking piece on this morning. In his daily Hook column, Ziller investigates whether the NBA is really “a young league”–at least relative to the past. Ziller offers a variety of interesting measures, but I think my database allows some that emphasize his point.

First, I looked at the league’s average age weighted by WARP–essentially the average age of a win produced. As Ziller points out, this is a slightly more meaningful measure for what we’re pondering than minutes-weighted age. Last year, the WARP-weighted average age of the league was 27.5, which is just a little bit lower than average for the 32 seasons for which WARP is calculated. The league was much younger in the early ’80s, at one point dipping below 27 for WARP-weighted average age. The NBA then got really old in the late ’90s. During the lockout season, the WARP-weighted average age reached an ancient 28.9 before getting back in the 27 range by the middle of the last decade.

What looking at this issue emphasizes is that there are two trends at play. Yes, players are entering the league younger and having success doing so, but they’re also aging better than ever, a topic I considered at length last season. Those two issues work against each other when we look at the average, so it probably makes more sense to look at the distribution of WARP by age. I grouped players into three buckets: those under 25 (the young), those between 25 and 30 (the prime) and those over 30 (the old). Check out a graph of how WARP has been distributed among these three groups over the last three-plus decades:

Chart of NBA Age

The way these buckets are set up should favor the players in their prime and almost always does, most dramatically so in the late ’80s. At the end of the ’90s, however, as a generation of players like Michael Jordan and Karl Malone aged better than we’d ever imagined before, the league suddenly got very old. At this point, there wasn’t a younger generation of stars successfully coming in to replace these veterans. Those young players did not really start taking off until the lockout season. Since then, we’ve yet to see such a dip in terms of young talent, so as that same generation of players comes of age, it’s the prime group that is relatively down. So it is that right now, the NBA is a young league, but simultaneously also an old one.

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