Saturday, February 27, 2016

The Hero Ball Index

In last year's conference semis, Lebron James, with just 1.5 seconds left and the game tied, hit a 21 foot shot from the corner to give the Cavaliers a victory over the Bulls, 86-84. Said James after the game:
I was supposed to take the ball out. I told coach, 'There's no way I'm taking the ball out unless I can shoot it over the backboard and go in.' So I told him to have somebody else take the ball out, give me the ball and everybody get out the way.
In clutch situations, teams tend to run their offense through their stars (or in Lebron's case, the star runs the offense). At its best, you get iconic moments like Michael Jordan's game winner in the '98 Finals and Lebron's aforementioned heroics. At its worst, you get low efficiency desperation, clock draining iso play, and heavily contested, off the mark mid-range jumpers (sarcastically referred to as "hero ball").

Earlier this season, I launched clutch shooting reports. This interactive report uses win probability to classify shots into four basic categories: garbage time, "normal" basketball, clutch, and "double" clutch. That fourth category, double clutch, represent the top 1% of shots in terms of potential impact on a team's chances of victory. The following chart summarizes these four phases as a function of score difference and time remaining.

Sunday, February 14, 2016


Some All Star break frivolity.

The earliest documented use of the term "air ball" dates back to a 1967 article in the Hayward Review:
Cal State, four times lofting air balls at an orange basket that may as well have been painted invisible.
The phrase shows up in broadcast as early as 1972, with none other than announcing legend Keith Jackson using the term to describe an errant shot by Lakers guard Gail Goodrich during game five of the 1972 NBA Finals. Jackson's pronunciation of the term is particularly Keith Jackson-y:

The infamous sing-song chant that now follows an air ball seems to have developed later in the decade. Duke fans (who else?) claim to have begun the first "air ball" chant in 1979, following a miss by North Carolina's Chick Yonakor.

Sunday, February 7, 2016

Are there "shooter friendly" NBA arenas?

Baseball, in contrast to most every other major sport, allows each team significant leeway in designing their home venue. Both the length and height of home run fences varies from park to park. In addition, regional differences in air density and humidity can have a significant impact on how far a baseball travels in flight. 

As a result, there are what is known as "hitters parks" such as the Colorado Rockies' Coors Field, where the thin Denver air results in more than two runs per game on average. And there are "pitchers parks", like San Diego's Petco Park, with its dense, dry sea-level air and distant home run fences that lead to, on average, roughly one less run scored per game.

Does a similar phenomena exist in the NBA? Are there "shooters arenas"? Of course, the NBA maintains far more uniformity across its venues than the MLB. The dimensions of the court do not vary, the free throw line is always 15 feet from the backboard, and the three point line is the same distance everywhere (basketball brainteaser: If you were playing the Warriors and given the option of re-drawing the three point line, would you make the line closer, or further away?). 

Saturday, February 6, 2016

NBA Games are not Getting Longer

With the NBA continuing to expand the types of plays subject to instant replay review, there was justifiable concern that these changes could lead to even longer games. I've done a lot (perhaps too much) research into the length of NBA games and what drives it, starting with a post on the average length of each minute of NBA game time. Subsequent work looked into the difference between close games and blowouts and the length of playoff games. Also check out the "Significant Other" calculator that is part of this site's live win probability graphs.

The NBA, never shy with the sharing of data, thoughtfully timestamps each play of every NBA game, which aids and abets all the aforementioned research. For this post, I will use those timestamps to examine trends in average game time, spanning the past six seasons. Were the fears of longer NBA games justified?

As it turns out, games are shorter than they were just a few years ago. And the expansion of instant replay does not appear to have made a noticeable impact on game length.