The value of inefficiency
Players who look for midrange shots aren't always a drag on offenses
By Neil Paine | Basketball-Reference.com
AP Photo/Matt SlocumAndre Iguodala keeps opponents honest by hoisting long 2s, even though his own efficiency suffers.
The Philadelphia 76ers have built an historically great defense upon the principle of forcing opponents into shooting long 2-point jump shots, but an unhealthy dose of midrange jumpers can kill a team's offense, too.
Per Hoopdata's stats, the only shot distance that has a significant impact on a team's offensive efficiency is the percentage of field goal attempts taken from 16-23 feet. That the impact is negative shouldn't be very surprising, either -- after all, the expected value of a given shot from that range this season is just 0.76 points per attempt. Put another way: if all else is equal, the difference between having the league's lowest percentage of shots from 16-23 feet (Denver's 15.5 percent) and its highest (Charlotte's 35.2 percent) is worth 6.5 points per 100 possessions. That's a bigger boost to an offense than replacing a league-average point guard with Chris Paul.
For all the hemming and hawing by purists over the "lost art" of the midrange game, the basic math on those shots appears to be quite damning. If the average player makes 38 percent of his shots from 16-23 feet -- shots that are still worth just two points -- and 35 percent on 3-pointers, why not eschew the long midrange jumper entirely and instead take a shot that gives you an extra point? That's essentially where the game is heading. In just six seasons, the league has gone from taking 26.9 percent of its shots from 16-23 feet to 24.5 percent. Simply, teams are learning to cut out the game's least efficient type of shot.This trend also tracks with the rise of individual efficiency stats. Almost universally, players who take a large percentage of their field goal attempts from 16-23 feet also have a low personal offensive rating, a useful all-in-one efficiency metric that tracks a player's expected points when he ends a possession with a shot, assist, drawn foul or turnover. Splitting up the 140 players who have attempted 403 or more field goals this season into four groups based on their percentage of shots taken from 16-23 feet, you can see a clear relationship between individual efficiency and the tendency to hoist midrange jumpers:
As was the case with teams, the more shots a player takes from midrange, the less efficient an offensive player he will be. Not only does he by definition take fewer high-efficiency shots at the rim or from beyond the arc, but he is also less likely to draw a foul when taking a long jump shot. Given this, convincing players to leave the midrange jumper out of their repertoire would seem to be an intelligent decision for any NBA team.
However, there is some counterintuitive evidence that players who have the midrange jumper in their arsenal still help teams score more efficiently while on the court. Even after controlling for a player's own rates of possession usage, shooting efficiency (as measured by effective field goal percentage, a stat that adjusts for 3-pointers being worth 1.5 times as many points as 2-pointers) and assists, the percentage of his FGA that came from 16-23 feet was actually a positive variable when predicting his impact on the team's overall effective field goal percentage. That finding was also true when running the same test on team turnover percentage -- the more of a midrange game a player has, the more he helps his team avoid giveaways.
Why might this be? One theory is that merely having the ability to score from the midrange opens the floor up for a player's teammates. According to 82games.com, just as 3-point attempts per minute is a positive predictor of offensive impact even after holding all other stats equal, players who can knock down shots from 16-23 feet force the defense to respect them from more places on the basketball court, which in turn creates precious space for other players. There's value in keeping the defense honest.
There's also the matter of a player's shot difficulty as it relates to his role on the team. Among players with at least 1,200 FGA over the past three seasons, high-usage perimeter players (players listed as guards or guard-forwards by Basketball-Reference.com) took a greater percentage of their shots from midrange than those with lower usage rates. While minimizing midrange shots is a good general rule at the team level, even the most midrange-avoidant teams take 15-20 percent of their field goals from that range, shots that high-usage players frequently have to create from scratch.
Take, for instance, the 20 highest-usage players in the league. As a group, these players are assisted on a much lower percentage of their field goals than the NBA average, because in order to consume so many possessions, a player must increasingly create scoring chances for himself. But even by those players' already self-sufficient standards, they get very little help on the 16-23 foot jumper.
Here are the percentages of assisted field goals by shot distance for the 20 biggest possession users, versus the league average (see chart):
At every other location, high-usage players are a uniform 13-14 percentage points below the NBA average in terms of requiring assists. But on 16-23 foot jumpers, that number zooms to 17.6 percent, meaning the degree of difficulty on midrange J's is upped considerably for the best shot-creators. Whether they're forced to shoot under duress at the end of the shot clock or trying other tough chances that no one else on the floor is willing to take, this increased difficulty explains why high-usage players are so valuable even if their efficiency isn't necessarily pretty.
Perhaps no player exemplifies this phenomenon more than Toronto's Andrea Bargnani. Despised by some in the stats crowd, Bargnani perennially takes 25-30 percent of his shots from midrange, and as a predictable result his efficiency metrics are always below average. Yet a regression to determine player impact on offensive Four Factors found that Bargnani's presence boosts the team's effective field goal percentage by 0.6 points and reduces his team's turnover rate by 0.3 points while he's on the floor.
For evidence corroborating his on-court influence, check Toronto's record with (13-18, 42 percent winning percentage) and without (7-19, 27 percent) him this season. On paper? Bargnani is the textbook high-usage, low-efficiency player. But his actual impact goes much further than that.
Of course, a more efficient player is preferable to a less efficient one, given the same levels of usage and shot difficulty. But the next time you see someone decry the midrange tendencies of a high-usage player with low efficiency ratings, remember that at least some of that apparent lack of efficiency is due to absorbing the (necessary) tough shots that inevitably arise during a game. By being willing to take those chances -- and make them at a higher rate than his teammates would -- the high-usage player sacrifices his efficiency stats for the good of the team as a whole.
原文标题:The value of inefficiency
原文作者: Neil Paine