This year's epic first-round playoff series between the Boston Celtics and the Chicago Bulls went seven games and included a total of seven overtime periods. "There were stitches, bloody towels, pain-killing injections, shoves, flagrants, technicals," wrote ESPN.com's Gene Wojciechowski after the final game on Saturday. Indeed, it seemed like the players on both teams were digging deeper than they had been through the six months prior. That's a familiar notion for many fans. In fact, the belief that NBA teams only go all out once they get to the postseason can be traced back at least three decades, to the film Airplane! In one scene, little Joey visits the cockpit and discovers that Kareem Abdul-Jabbar is the co-pilot. "I think you're the greatest," Joey says, "but my dad says you don't work hard enough on defense. And he says that lots of times, you don't even run down court. And that you don't really try … except during the playoffs."
It's probably human nature to try harder when the stakes are higher, so let's assume that Joey's dad is right, and NBA players don't give their best effort until the playoffs. Is there a way we could prove it statistically? We love to ponder questions like this at Basketball Prospectus.
There are a couple of obvious pitfalls in trying to quantify the effort of a professional basketball player. First, if it's true that players work harder in the postseason, then both teams should be equally affected, at least in the aggregate. Statistically, you're talking about what economists might call a zero-sum environment. That is to say, a team or player's gain or loss is canceled out by the gains or losses by the opposition. (If one player is trying harder on offense, then his opponent is trying harder on defense, too.) In the attempt to measure something as intangible as effort, this poses no small problem. Still, it might be possible to tease out some broad effects that show up nevertheless.
One thing we know is that the version of NBA basketball you see in the playoffs is slightly different than what you see in the regular season. The pace is slower. Since the ABA-NBA merger in 1976 (which happened to coincide with the league's decision to track all the numbers needed to calculate possession-based statistics), playoff games typically average between three to five possessions fewer than they do during the regular season. Teams are also more careful with the ball: On a per-possession basis, turnovers decrease by a little more than 5 percent. Finally, teams are less prone to settling for outside shots. You can see this effect numerically by the increase in fouls drawn—the ratio of free throws made to field goals attempted goes up by almost 7 percent in the playoffs.
These numbers don't in themselves suggest that teams are playing harder. Some of the changes can be explained by the types of teams that make the playoffs in the first place: Maybe the clubs that take it slow and attack the hoop tend to win the most games during the regular season and advance farthest in the postseason.
How to address such a murky question? Let's invent a new statistic! Basketball analysts love to do this, in part because, like astronomers, we get to name our new discoveries. In this case, we'll name our new metric after the player who best typifies the hustle-over-talent ideal: We'll call it RAMBIS.
First, we need to decide which statistical categories are the most "effort-based," so we can figure how to combine them into a RAMBIS number. This isn't an easy task, since lackluster effort would show up throughout the box score. However, after some hand-wringing and linear-regressing to determine which statistical categories changed the most from the regular season to the playoffs, we settled on four team measures—two based on offense and two based on defense.