On Volatility Among The NBA's Top Scorers

LeBron James is the most consistent of the NBA's top scorers. What's that worth? Who are the most volatile scorers in the league?
Follow @sbnation on Twitter, and LikeSBNation.com on Facebook.
Feb 2, 2012 - As we know based on the wide range of shooting percentages we see among the list of the NBA's top point producers, we know that not all scorers are created equal. Kobe Bryant is scoring a bit more than LeBron James per game this season, but Kobe needs four extra shooting possessions to reach that level. Carmelo Anthony is the league's No. 5 scorer, but takes more shots per game than two of the guys (Kevin Durant, Kevin Love) ahead of him on the list.
There's another way in which scorers differ: volatility. Some scorers are more reliable than others; there are the proverbial "you know you're going to get 20 points" guys and the "explosive scorers." We sometimes give credit to explosive scorers, even those in prominent offensive roles, because they could go off at any time and get their team back in the game.
But there's a flip side to that: they aren't necessarily dependable. In the NBA as in any competitive atmosphere, consistency has some importance. If a team's management doesn't know what they'll get out of a star any given night, it's hard to build a proper cast around him. Just how much of a drain excessive volatility is a question mark, at least for this column. (I have no doubt a team or three have conducted studies on the value of consistency, but there's nothing public or publicized in the NBA realm on that issue that I know of.) This exercise is meant to look at which players are volatile compared to their peers.
There are currently 15 players who have enough minutes to qualify for the leaderboards who are averaging 20 points per game this season, ranging from Dwight Howard's 20.1 average to Kobe's 30.0. To measure their scoring volatility, I borrowed a trick from finance: I took the standard deviations of the players' game-by-game scoring totals and divided by their scoring average. This gives us a volatility rating that allows us to compare 30-point scorers with 20-point scorers without bias.
What we found is not wholly surprising: 'Melo, who this week actually had a 1-point game, is the most volatile of the 20-point scorers this season, and not by a small margin. Anthony's game-by-game standard deviation is nearly half the size of his scoring average; he is almost as likely to have an extreme scoring performance (more than 34 percent above or below his average) as he is to have a normal one.
Howard, surprisingly, is right behind 'Melo. Seeing a big man so high on the list fights conventional wisdom, which is that since big men tend to have higher shooting percentages, their production is more reliable. While Kevin Love, Blake Griffin and LaMarcus Aldridge all seem to bolster that hypothesis with relatively low volatility marks, Howard -- a regular near the top of field goal percentage rankings -- is a blinking signal of doubt.
One possible explanation: Dwight earns so many free throw attempts and shoots them so poorly that if he has a bad day at the stripe, he's likely to have a bad day in the scoring column. (That the season has been short and that he had a monster scoring game against Golden State could affect things too, though the game didn't throw his average too far away from expectations.)
The other numbers aren't terribly surprising. LeBron is a clock; he's had just two games under 20 points in 21 outings and none under 16. Kevin Durant is similarly stable, with the second lowest volatility rating among the 20-point scorers. Chris Bosh is, other than Howard, the most volatile of the high-scoring big man, likely owing to his rare role as a third option on offense. (Not many third options average 20 a game.) Monta Ellis and Brandon Jennings live up to their reputations as "explosive," and Russell Westbrook looks more like Derrick Rose every day.
Again, we don't know how important volatility in scoring really is, so it's hard to place value on the predictability LeBron, Durant and most of the big men provide. But it's worth keeping an eye on as we suss out our expectations for what players can provide and how consistently they should do so.