Bettors are always after a kind of holy grail – a statistical model that will allow them to predict the results of sporting events more accurately.
Ever since sportswriter Henry Chadwick invented the box score in 1858, writers, fans, and athletes have looked for ways to gain insight into the game using numbers, past performance, and trends.
Once upon a time, plain stats like field goal percentage and raw counts of offensive and defensive rebounds were all that fans, bettors, and coaches had to evaluate play. An explosion in sports statistics and mathematical modeling, a result of the work of baseball fans and mathematicians Earnshaw Cook and Bill James, has led to new ways to look at and predict sports performance.
This post is all about the 4-factor method of NBA analysis. I’ll identify 4 offensive and 4 defensive advanced statistics you should use to analyze team performance and better understand a team’s strengths and weaknesses.
Evaluate NBA Offensive Performance with These 4 Factors:
Looking at teams’ offensive performances through the 4 lenses below, weighting them equally, and considering a team’s holistic abilities in these 4 areas, gives you a good sense of where these teams are strong and where they are weak. Here are the 4 offensive factors in NBA performance:
1. Effective Field Goal Percentage (EFG)
The purpose of Effective Field Goal Percentage is to give a better picture of a player or a team’s shooting abilities than plain-old FG%.
When you compare two teams by their FG%, you’ll often see the winning team with a lower rate. EFG adjusts this by giving 3-point shots more weight.
Notice that this formula weights 3-point field goals 50% more than two-pointers (thanks to the 0.5 multiplying factor that precedes the 3-point field goals made stat. The purpose of this is to honor the fact that a 3-pointer is worth 50% more points than a 2-point field goal.
2. Turnovers Committed per Possession (TPP)
Over the past ten seasons, NBA teams are averaging 93 possession per game. TPP gives us a sense of how often teams are giving up those possessions to the other side.
3. Offensive Rebounding Percentage (ORP)
This is self-explanatory; ORP is the percentage of rebounds a team gets off their own missed shots.
4. Free Throw Rate (FTR)
This is simply foul shots made divided by field goal attempts, giving you a sense of how often a team gets to the free-throw line and succeeds in adding a point.
Identifying Offensive Weaknesses Using the NBA 4 Factors
Let’s look at some real-world examples of NBA performance through the lens of the 4 offensive factors.
Three teams leading the NBA in terms of winning percentage are the Phoenix Suns, Golden State Warriors, and Utah Jazz.
Phoenix has an incredible 21- record, with Golden State right behind at 21-5, and Utah trailing at 19-7.
What about the team with the worst Effective Field Goal Rate? That would be the Detroit Pistons, at 7.%, making them just about 10% less efficient than the best teams in the league. Detroit currently has the worst winning percentage, taking the W in just over 15% of their contests.
Likewise, the Suns seem limited by their FTR, which is 22.6%, a middle-of-the-pack number that gives away something bettors and fans have known for a long time – this Suns team is a lot less experienced than recent iterations. Youth and inexperience often show up in the FTR stat, and that’s the case here.
Evaluate NBA Defensive Performance with These 4 Factors
Basketball is a two-way game; few other sports involve players switching back-and-forth from offensive to defensive roles as rapidly as the NBA.
It’s important to evaluate and understand team defense – in some cases, like the playoffs, it may be more important than evaluating team offense.
The 4 factors below are just a kind of inversion of the offensive 4 factors. For the most part, these are the matching stats for defenses based on the 4 factors for offensive performance.
Opponent’s Effective Field Goal Percentage (OEFG)
This stat tells you how often a team’s opponents score, and how many points those opponents manage to put on the board.
Defensive Turnovers Caused per Possession (DTPP)
This is the defensive inversion of the TPP offensive stat. It tells you how often a team’s defense is causing a turnover, producing the stat as a percentage of all opponent possessions.
Defensive Rebounding Percentage (DRP)
This stat tells you how often a team’s defense is taking possession after an opponent’s missed shot.
Opponent’s Free Throw Rate (OFTR)
This tells you a team’s average opponent FTR, which is a ratio of their free throws made to field goals attempted.
Identifying Defensive Weaknesses Using the NBA 4 Factors
Interestingly, the three winningest teams in the NBA are among the top-5 defenses, at least when you consider team defense through the NBA 4 factors method. But there’s a surprise in the defensive 4-factor stats for the 2021 NBA season.
If you compare all 30 NBA teams by their OEFG%, Golden State, Phoenix, and Utah come in 2nd, 3rd, and the place respectively. The top team in terms of holding their opponents to poor shooting performances is the Brooklyn Nets, with a respectable 19-8 record, but not exactly one of the best teams in the league.
What’s limiting Brooklyn? If they’re able to hold their opponents to 9.1% shooting, and they are shooting at a 53.3% EFG, why don’t they have a winning percentage in the high 80s or 90s?
Only five teams have a worse DTPP than the Nets, which is clearly a limiting factor for the team. Combine this with a relatively high opponent offensive rebound rate (28%, the 9th-worst in the league right now), and it’s easy to see why you have to consider all the factors when evaluating team performance.
We can also see a major weakness for the Utah Jazz by looking at the defensive 4 factors – their opponents are pulling in 26.2% of their rebounds, which isn’t bad by league average standards but is by far the most disappointing stat among all the 4 defensives and 4 offensive factors.
The Jazz have succeeded this year by occasionally going small – they score a lot when they do that, but they also lose the ability to win rebounds. It’s a kind of devil’s bargain – how long can you afford to score small?
Looking at the 4 NBA factors won’t automatically make you win more of your NBA bets.
But it’s a powerful system for handicapping and evaluating performance, in that it’s elegant, the stats involved are publicly available (for free), and it can cut the time required to seriously assess a team’s abilities. It’s one of many such methods, and it’s not the only successful method ever devised.
Its power lies in its simplicity, and in the straightforward way it points out assets and liabilities across NBA squads.