Exploring the Relationship Between the Consistency of Starting Lineups and Win Percentage in NBA
If it ain’t broke, don’t fix it.
This well-known proverb from the subtitle can be applied to many things, one of them being NBA teams’ starting lineups.
Injuries, performance, emerging rookie/sophomore, schemes… Those are some of the reasons an NBA team would change their starting lineup throughout the season. And they usually make a change when things are already broken. This means that we should have a pretty clear (inverse) relationship between a number of starting lineups and win percentage.
Motivation for the Post
Even though I’ve played around with this idea early in the season, I didn’t go into the detail about the relationship with win percentage, but I did “hint” that the Pels, Cavs, and Heat could improve with time, as they were shaken up with injuries at the start. The Cavs got into even more injury issues, The Heat are constantly without one or two starters, but the Pelicans got healthy and are getting into the rhythm as the season went on.
A Recent Spark
But a new “spark” to go a bit more in-depth about this was this recent tweet by Iztok Franko, Mavs’ analyst who gives great insights after every game and finds a lot of interesting data tidbits about both Mavs and their opponents. In the linked tweet, Iztok talked about Thunder’s health and how that helped significantly in propelling them to the top of the conference.
Current Season Numbers
As you can see in the chart, Iztok’s Mavs are the worst in this segment, as they have had exactly 21 different starting lineups out of 37 games which comes out to 56%. Along with them, the Pistons, Heat, Blazers, and Grizzlies are also hovering around the 50% number.
The Wizards, Rockets, and Wolves have been the most consistent with their lineups thus far. Let’s go ahead and take a look at how, and if that helped their win%.
Relationship With Win%
The first thing that catches attention is the top-left part of the chart, as the Wolves, the Rockets, and the Thunder are the best teams currently when it comes to outpacing their projected win percentage. They are also among the top 5 in terms of consistency of starting lineups. The Wizards are an outlier on this part of the chart, as they’ve been tied the healthiest team but are playing poorly and underperforming according to the Vegas.
On the other side of the lineup consistency spectrum, we have the Pistons with a historically bad season, while the Heat and Mavs managed to stay right around the projected win percentage, and are on pace to cover the o/u wins spread given out by Vegas at the start of the season.
The Mavs and The Heat could be a pretty solid candidate for a dark horse come playoff time…
Is There Any Correlation?
When we look at the chart as a whole, we can generally notice a pretty significant negative trend, as the win% vs projected win% is falling with the number of lineups changed.
If we take a look at Spearman’s correlation coefficient we get a value of -0.406 which would represent a moderate correlation. This confirms that starting lineup consistency helps teams win more games.
A Look in the Past
Through the 2022-23 season, we’ve had a relatively similar trend. The Kings were last year’s Wolves/Rockets, as they’ve had a ridiculously healthy season with only 9 unique starting lineups, and outperformed their projected win percentage by a hefty 15%+.
The teams that reached the finals in the end were the Nuggets and the Heat. the Heat were a huge underdog last year, and it was a season with similar patterns as in this one, lots of roster turmoil and injury riddles that mostly resolved come playoff time (except for them losing Herro for practically the entire playoffs…).
The Kings flopped in the first round of the playoffs in a tough matchup vs the Warriors. Despite that, no one would say that their season was a failure, as they were only getting back to the winning tracks.
Last year’s number gives us Spearman’s coefficient of -0.247 and that would be a small correlation. It is possible that current season’s numbers will lose correlation strength as we get deeper into the season, mainly due to teams regressing in terms of performance.
A Look Towards the Playoffs
We are approaching the 50% mark of the season fast, and we’ve had several pretty healthy outliers. Those teams also happen to be new faces when it comes to playoff basketball. It will be interesting to see how will they react to the new surroundings when the more experienced teams - but also more injury-ridden teams - turn up the engine.
Nevertheless, the Wolves, the Thunder, and the Rockets have all shown great basketball on the court, and even if their playoff trips come short this season, they have solid foundations for the future and even more success in the following seasons.