Simple Rating: Part One of a Primer on Advanced Statistics

Nearly forty years ago, the writings of Bill James began to change the way people thought about baseball.  James’s yearly Baseball Extract was a break from the usual way that people wrote about the sport, and in some ways, foreshadowed the blogging revolution. James’s writings were statistically-based, and attempted to go beyond the typical box score numbers to develop new ways to evaluate players.

James introduced the concepts of secondary average, runs created, win shares, and similarity scores (among others) to the baseball lexicon. Over time, these statistical concepts became widely accepted in major league front offices and increasingly discussed by fans when debating their favorite players or teams.  Even the crustiest baseball scout has been forced to accept that it’s more than just the “eye test” that shows the true value of a player.

Over the last 15 years, a similar revolution has taken place in basketball. There has been an explosion of statistical metrics used to better analyze what is happening on the court.  Some of them are extraordinarily complex and generate insights that fly in the face of conventional wisdom.  But if you’re a newbie to the concept, it can be daunting to understand them.

So let’s start simply – literally – by looking at a metric called the Simple Rating.  Simple Rating is a statistic that gives you a good baseline on the relative value of a player – it’s most useful when comparing players on the same team, but gives you a good general sense of a player’s overall value as well.

The Simple Rating has two components – Production and On Court/Off Court.  Production is a form of John Hollinger’s Player Efficiency Rating (PER), which is one of the earliest advanced stats to gain widespread traction.  PER attempt to boil down all of the traditional box score statistics (points, field goal shooting, free throw shooting, offensive and defensive rebounds, steals, assists, blocked shots, personal fouls and turnovers) into an all-in-one rating that is adjusted to produce an average rating of 15.  For the Simple Rating, one evaluates a player’s PER while he is on the court versus his opposing player at the same position.

For instance, last season, Kevin Love had a Production rating of 29.0, while his opposing power forwards had a production of 15.8. With rounding, Love’s Production component was +13.3. (If your production was lower than your opposing player, your Production component would be negative.)

The second component of Simple Rating is On Court/Off Court.  This component measures the team’s performance when the player is on the court versus when they are on the bench expressed as a rate of per 100 possessions. This is a similar concept to the plus/minus statistic in hockey.  For instance, a player who starts the game and then leaves after 10 minutes with his team leading 20-16, would count as +4 for that period of time.

Last season, when Kevin Love was on the floor for the Timberwolves, the team was 6.1 points per 100 possessions better than their opponents. When Love was on the bench, the Timberwolves were 5.6 points per possession worse than their opponents. As such, Love’s On Court/Off Court component was +11.7. (Again, if your team performs better with you on the bench, your On Court/Off Court can be negative.)

To calculate Simple Rating from the two components, you count the Production component as 2/3 of the total, and On Court/Off Court as 1/3. Doing so for Kevin Love as shown above gives him a Simple Rating for 2013-14 of +12.8 (fifth best in the NBA among players who played at least 40% of their team’s minutes or 20 minutes/game).

What does this tell us?  Some of the insights are fairly routine.

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Most of the names that come in near the top of the lists of best Simple Rating are players recognizable as among the best in the game.  But it also highlights the impact of some lesser-known payers. For instance, the most recognizable names on the East-leading Atlanta Hawks are inside players Al Horford and Paul Millsap. But it’s the backcourt of Jeff Teague and Kyle Korver that stands out looking at the Simple Rating. Korver, in particular, is having a remarkable season, shooting over 50% from three-point range on six attempts per game.

What does Simple Rating tell us about the local club?

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Simple Rating confirms the value of injured veterans Kevin Martin and Nikola Pekovic – who both outproduce their opposing player and have positive on court/off court numbers.  It shows that the improvement of Shabazz Muhammad in his second season is not merely the result of a player racking up stats on a bad time. Most crucially – in a positive sense – is that it shows the value of Ricky Rubio. Rubio’s 2014-15 Simple Rating follows the general pattern seen the rest of his career, but amplified. On an individual level, Rubio tends to be slightly outproduced by other point guards, but his impact on the team as a whole while he is on the floor is immense.  Certainly, part of this impact can be traced to the relative weakness of his backups (Mo Williams and Zach LaVine), but it also reflects the real value of Rubio’s defense and his ability to run an offense.

On the negative side, Simple Rating confirms that LaVine just isn’t ready to be a NBA player yet. Of all players who have played at least 40% of their team’s minutes, LaVine has the worst Simple Rating of any player in the NBA.  To put it another way, replacing LaVine in the lineup with a player with a 0 Simple Rating would be the rough equivalent of adding Demarcus Cousins to the Timberwolves lineup without trading away any assets.

It also shows that, although promising, Andrew Wiggins and Gorgui Dieng have a ways to go yet before they can truly be considered productive NBA players.   Wiggins’ strong run of play over recent weeks is lifting his rating (his current production stands at 12.8, compared to the 11.9 shown above through 1/7), while Dieng’s struggles on defense are evidenced by his negative Production rating (the average center who lines up against Dieng is producing at an All-Star level).

Simple Ratings aren’t flawless.  The Production Rating may tend to overvalue inefficient scoring and undervalue players who are strong defenders without racking up blocked shots or steals (think Bruce Bowen). On Court/Off Court figures can be distorted by unusually strong or weak benches and who a player plays with regularly. But they do serve a useful purpose as a general metric to evaluate player performance and as a way to get introduced the methodologies that carry through to other advanced statistics.

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