UNDERSTANDING PLAYER EFFICIENCY RATINGS
Editor's Note: Harris W. ('16) uses mathematics to comprehend the meaning behind basketball player statistics.
The world of sports is an ever changing landscape. Basketball is no exception to this. If fact, basketball is, in many ways, leading the charge towards what many consider to be the most important innovation in sports in a long time, advanced analytics. Today, NBA front offices use all sorts of different metrics to determine the value of a player, from defensive rating to effective field goal percentage. However, there is one metric, which, for better or for worse, has become the most well-known, and the most commonly used. This statistic is Player Efficiency Rating, and its use is essentially spelled out in the name. It is designed to determine a player’s effectiveness while they are on the floor. The man who came up with the formula, John Hollinger, put it like this, “To generate PER, I created formulas -- outlined in tortuous detail in my book "Pro Basketball Forecast" -- that return a value for each of a player's accomplishments. That includes positive accomplishments such as field goals, free throws, 3-pointers, assists, rebounds, blocks and steals, and negative ones such as missed shots, turnovers and personal fouls.” The actual formula for calculating player efficiency rating is both long and complicated, but has been parsed out in John’s book, Pro Basketball Prospectus. The widespread use of this particular metric has a few reasons, some of which pertain to the actual statistic, and some of which are more based on marketability. The end game of basketball analytics is to find one statistic that can determine the value that a player has to a team. Within the analytics community, it is essentially agreed upon that this is not likely to ever be found. This does not stop people from trying to come as close as possible as they can to one. And it will be argued by some that Player Efficiency Rating is the closest there has ever been to an ultimate statistic. However, there are many detractors that say that PER is either wholly unreliable or simply not a statistic that should be as commended as it is. The issues, some of which Mr. Hollinger has conceded to, are very glaring. For one, it does not take a player’s defensive ability into account. This is because, other than very simple stats such as blocks or steals, there really isn’t a mainstream statistic that calculates a player’s defensive worth. The first time that someone learns about Player Efficiency Rating, it is not unreasonable to think that it should act as a way of evaluating all players against one another. Because it is condensing the value of a player on a per minute basis, you would assume that there is a finally a mathematical way to determine who the best and worst players in the league are, and in order. People try to do this all the time in their heads. Long before Player Efficiency Rating existed, there was a constant debate over who the best and worst players are. Despite, the development of this statistic, that debate rages on. Much of this is due to the fact that players that would not traditionally be thought of as top tier players have some of the highest PERs. One player that exemplifies this enigma is Brandan Wright, who, throughout the season, has played for Dallas, Boston, and Phoenix. As it stands today, Brandan Wright has the 26th best PER in the NBA, with a Rating of 21.05. This means that out of the 357 players that qualify for the statistic, Brandan Wright is in the 93rd percentile. If one were to simply look at this stat as a way to quantify the value of a player, they would say that he should be a key cog on any team. However, he has always been, with the season being no exception, nothing more than a role player. So why is it then, that a player can consistently comes off the bench and still be in the upper echelon of Player Efficiency Rating. For one, his game is a lot about efficiency because for much of the season, he hardly missed any shots. True shooting percentage is a statistic that is used to find a more accurate representation of a player’s shooting percentage than the more basic stats. The equation is:
Brandan Wright has the third highest true shooting percentage in the league, which is very good, but when it comes to the box score, that’s really all he does. He only averages 4.1 rebounds per game, which is 39th out of 59 total centers in the NBA. So the reason for his high PER is that because it is a per minute statistic, these numbers are inflated by that lack of minutes that he plays. Projecting his statistics per 36 minutes, he has some of the more impressive numbers in the NBA, however, there are reasons that he can’t play 36 minutes a game, while a player such as Lebron James can play 36.3 minutes a game. Wright’s lack of a varied offensively skill set makes it difficult to do too much of offense, which can be detrimental to a team throughout the flow of a game. Something else that he does on a frequent basis is foul. When a player is constantly fouling the other team, he needs to be kept on the bench for a longer period of time than a player that won’t foul because he is more likely to foul out of the game, and the other team gets to take foul shots, which players make at a higher frequency than any other shot, except for layups. All this being said the highest PERs in history do belong to some of the greatest players. The top three are Michael Jordan, Lebron James, and Shaquille O’Neal, three surefire hall of fame players.