PLUS−MINUS (+/−) (±) (PLUS/MINUS)
Plus-minus is a sports statistic that originated in Canadian hockey in the 1950s and was officially adopted by the NHL in 1967/68.
Although it has been tracked and used in the NBA since 1973, it did not become an officially adopted ‘box score’ until 2007/8.
In this article, we’ll take a closer look at what the term means and try to explain the pros and cons of some of the more complex versions that have appeared.
Stat-nerds like the team here at The Jump Hub are in their element when dealing with in-depth numbers and subtle trends.
We love nothing more than poring over lists of box scores and obscure statistics in a (usually unsuccessful) attempt to gain some advantage over the online sportsbooks for the next round of games.
Ironically, plus-minus data is actually rather more useful in analyzing NBA games and players than it is of hockey ones, as the higher the scores are, the more effective it can actually be.
WHAT DO PLUS-MINUS METRICS REPRESENT?
Plus-minus values are used to determine an individual player’s impact on the game, as represented by the difference between their team’s total scoring versus their opponent’s total scoring when they are on the court.
It boils down to this – when any given player is on the court, does his team score more points than their opponents, or vice versa?
The plus-minus metric can be applied to any period, from a segment of one game to full games, multiples of games, or even seasons.
It does seem to yield more useful results over the long term and could be considered a very ‘raw’ statistic on the face of it.
It would surely be wholly inaccurate to attribute swings in scoring during a game to the appearance or disappearance of one player.
There are myriad other factors that must come into play?
That is where some of the ‘advanced’ plus-minus stats systems come into play and attempt to pick up any shortfalls, but more of that later.
We’ll take a hypothetical game
Chicago Bulls @ Golden State Warriors
and focus on 2 players that we think we might like to place a bet on in the future.
Alex Caruso (Bulls) and Stephen Curry (Warriors)
As the game begins, both men have a plus-minus rating (+/-) of 0 (for this game only)
Nobody has scored yet.
The Warriors take first blood and score a 2-pointer (the actual scorer is irrelevant for this particular stat)
This now gives Alex Caruso a plus-minus value of -2
Whereas Stephen Curry has +2
IT’S LITERALLY AS SIMPLE AS THAT
The plus-minus value represents the net gain or loss of that player during his time in the game and that’s all.
Until one or other of them leaves the court, this continues and the difference is recorded.
There are a variety of other potential combinations, including the best 2, 3, and even 5-player unit combinations for each game.
Modern basketball analysis contains a mind-boggling amount of advanced statistics and complex metrics. They attempt to help us better understand player and team performances.
We have progressed way beyond the days of simplistic, incontrovertible statistics. Showing things like points, rebounds, and assists during an NBA game in the form of box scores.
These still help us to see at-a-glance representations of a player’s impact on the court and fans of these stats (ourselves included) need not worry.
THEY ARE CERTAINLY NOT GOING ANYWHERE
It is for those among us who crave ever more detailed information and input on how a team plays that some new advanced stats systems have emerged and become more popular.
One that has garnered a lot of attention recently is a variation of the plus-minus system that goes a step (well, several hundred steps) further.
It’s insanely complicated, using a sophisticated model that can be adjusted by the user to add or remove elements as they choose.
This is not the time or the place to try and explain it all (did you guess that it’s because we couldn’t?)
So here it is in simple terms for the casual fan.
ADJUSTED PLUS-MINUS (APM)
Lauded by some (a little over-enthusiastically for our tastes) as the ‘ultimate’ replacement for box score statistics in the modern world.
The basic goal of APM stats is to also account for the other players on the court when attributing a player with a total.
Even the least statistically astute observer can see that plus-minus stats are very vague.
Yes, we can see how many points transfer in either direction from when one player enters the court to when he leaves again.
BUT REALLY, THAT’S ABOUT IT
They record any net changes that occur but give us nothing in terms of his actual playing contribution during a single game.
HE COULD HAVE BEEN TYING HIS SHOELACES THE WHOLE TIME FOR ALL WE KNOW
APM takes into account the other players on the court and compares the player in question against a hypothetical ‘average’ player. It assumes that they will typically take part (as a team) in 100 offensive and 100 defensive possessions played per game.
The statistician can control the model to incorporate external elements such as playing time, coaches, the recent match-ups with this particular opponent, down-time in between contests and so much more.
All in an attempt to build a kind of league average statistical baseline that they can use to compare other players against.
IF IT SOUNDS COMPLICATED, THAT’S BECAUSE IT IS!
Adjusted plus-minus ratings have a high degree of variance and can change pretty dramatically over the course of an NBA season.
A different role within the team, a different coaching scheme, changing teammates, different match-ups, or different seasons.
All of these things affect APM and it can be difficult to assess by how much.
Adjusted plus-minus is certainly a stat system that makes for some interesting reading and, if players were robots then we have no doubt that it would be startlingly accurate.
BUT THAT’S ITS ACHILLES HEEL
Players are not automatons. They are unpredictable and flawed at times. During a long league season, they have inexplicable periods of high-intensity and constant scoring, followed by barren times when they can’t score for love nor money.
No system can take into account a player’s mental attitude going into a game. Focus and constant effort are things that we expect of our sports stars. But it is all too easy to forget that they are only human.
We are so used to them performing near super-human feats, often the likes of which we have never seen before as athleticism and skill grow year upon year, that we have begun to take them for granted.
No stat model can tell us that a player had a fight with his wife and is not 100% focused on the game.
Or that he got the pep-talk of a lifetime from his coach at half-time and is energized and motivated beyond belief.
AND THAT’S WHERE YOU COME IN
Tools are nothing without a skilled craftsman.
Learning to select the right tool for the job can be tricky when there are no instructions that work all of the time so you are going to have to figure that out for yourself.
Nobody loves a good stat more than The Jump Hub crew, but we have learned to use each of them sparingly and to throw in a good measure of gut-instinct and current events before we make any bets.
We take a sample of many different items from the grand smorgasbord of stats that make up the NBA buffet and take time to digest them.
STAT BUFFET RULES:
Don’t overfill your plate! We’ve all got eyes that are bigger than our bellies, so choose wisely as, if you’re not careful, you won’t have room for everything.
Find your favorite item and make sure you get plenty of that, but leave room for sides. We all gravitate towards the stats that speak to us most and that’s a good thing. If you think that assists and rebounds best represent a player in form then fill your boots with those, but don’t neglect that plus-minus gravy.
It’s a marathon, not a sprint. You can always come back for more. This is a never-ending buffet, so don’t go mad and think you have to stuff everything in your face at once. Take time to think about what each stat might represent in your wider scheme and understanding of the game before smothering it with something else.
Ok, that’s enough food analogies for now, but you get the picture.
Take playing samples and stats from wherever you find them to be most useful.
Build yourself a betting strategy (if that’s what this is for) and tweak the ingredients as you go (ok, there was one more. That’s it now I promise)
Apply your findings to one NBA game and see how it works out.
Make changes if necessary and go again.
Which elements that you used held true to what you expected and played out how you wanted them to?
Check out our article on NBA Betting Strategy – A Guide to Placing Bets on the NBA for a much more in-depth look at this process.
When it comes to NBA basketball analysis, the best players and teams in the league have an edge over their opponents in a number of ways that extend way beyond just points scored.
It might be something tangible that we can see as it happens. ‘When this player enters the arena, this happens’ etc…
But that does not tell nearly the whole story. Nobody in NBA history has ever played an entire NBA season and conformed with every stat that they were supposed to.
Even peak Jordan wasn’t…. well, ok – there are exceptions to the rule, but not many.
IT CAN’T BE DONE
Humans are too unpredictable. And that’s why we love watching them play sports. We can never be truly sure of the outcome. Any given team can have a blip. Maybe they play teams where the other side has a huge point to prove and raises their game accordingly.
A team’s performance can be consistently amazing one season. Every player contributes to their maximum capabilities and makes a difference to the team.
That exact same team can step out the following season and be mediocre for half their games. Why?
Because they are not machines. Traditional stats cannot accurately represent the factors that affect them. Nor can the most complex and detailed models known to man.
WHAT CAN WE LEARN FROM PLUS-MINUS?
If we’re talking about basic plus-minus metrics, then rather than tracking a player’s individual accomplishments, the idea is to show how their cumulative contribution affects their team while they’re on the floor.
This can perhaps show wider trends and general effects of how a team performs when viewed over a longer period and not a single game.
It is a good way to make some wagers if you feel confident of the range of a particular player’s contribution.
Beyond this, the details will vary wildly depending on the model. ESPN’s Real Plus-Minus model has an element of official box scores involved and also factors in teammate and opponent context for each individual player. It is certainly one of the more complicated stat systems out there but the new version, in particular, has become a trusted tool for many bettors in terms of its generally high level of accuracy.
THE TRUE ANSWER LIES…
in a combination of studying and absorbing the stats that you feel a close affinity to. Then throwing in a whole heap of gut instinct and knowledge gained by studying other areas of the game.
Maybe you’re aware that a player has recently been having problems with fitness, or heard rumours that they are unhappy with the coach because they’re not getting enough playing time. Those are key pieces of information that many models cannot know or quantify.
Real plus-minus might seem to be a rather blunt tool in dealing with the intricacies of the NBA. But who said that all the tools in the box had to be sharp?