Posted by Neil Paine on September 7, 2010
Several times in the past, I've looked at what I called "Team Continuity" -- that is, the amount of minutes/possessions/etc. that a team gave to players who had been on their roster the year before. Today, I want to extend the concept to the NBA as a whole and examine league continuity, specifically the 5-year periods since the merger in which the league had the biggest influx of new talent.
How do we measure that, though? Just like with teams, I can look at the percentage of league minutes that were given to players who were still in the NBA 5 years later:
|Year||Y+5||Total MP||In NBA Y+5||Pct|
In other words, the 1995 NBA had the most 5-year continuity of any season since the merger, as 71.5% of the league's minutes that year were given to players who were still active in the 2000 season. Conversely, the very first postmerger season (1977) had the lowest 5-year continuity -- only 48.2% of NBA minutes that season were given to players who were still around in 1982.
Now, here's another take on the same data, this time looking backward instead of forward... This table gives the percentage of league minutes earned by players who were in the league 5 years earlier:
|Year||Y-5||Total MP||In NBA Y-5||Pct|
Again, you interpret this by saying that 53.8% of NBA minutes in the 2000 season were given to players who had been active 5 years before, in 1995.
What's the takeaway from this? Well, for one thing, the mid-to-late 1990s (and, to a lesser extent, the 2000s-2010s) were a great time for NBA job security and continuity among players. Both methods show that if you were an active player during that era, there was better than a 50-50 minute-weighted chance you'd be drawing an NBA playcheck 5 years later. As for the reasons why this was the case, anecdotally we saw stars enter the league earlier (often from high school) and enjoy more staying power thanks to modern medical practices that were absent from the league's earlier periods. But perhaps the biggest factor was simply expansion: the NBA went from 23 teams in 1988 to 29 in 1996, providing nearly 100 new jobs to fill (and maintain) that didn't exist in the past.
At the other end of the spectrum, all methods point to the immediate post-merger era as the span when continuity was at its lowest. Obviously new players joined the league directly from the merger in 1977, but this study doesn't even include that break in continuity; instead, it's the influx of players even after the Spurs, Pacers, Nets, & Nuggets were added that's being captured. The standard (read: lazy) explanation would be that the acceptance of the ABA led to an adoption of new playing styles, including a faster pace and more trapping, pressing defenses, which in turn created less continuity as the NBA struggled to find players who could adapt to the changes in play. The problem with that explanation, though, is that it's not even necessarily true: pace actually went significantly down within 5 years of the merger, from 106.5 possessions per game in 1977 to 100.9 in 1982!
So what's your take? Why do you think the league saw such major personnel turnover from 1977-1982/83?