Tuesday, March 27, 2007

THERE OUGHT TO BE A RULE: Moving the 3-Point Line

With the season winding down it's the time of year when many people take a step back from the game and start thinking about how to make it better. One of the ideas that seems to be popping up with greater frequency these days is moving the three-point line back. The three point shot, some say, has become a matter of too little risk and to great a reward for offensive teams. Moving the line back nine inches (to the international distance) or a foot (to an otherwise arbitrary point on the floor), they say, would restore balance to the game.

I've been inclined to agree with that argument. It seems like these days just about everyone is able to knock down a three point shot. ACC teams, for example, hit just over 36% of their three point attempts in the 2007 season, giving a three pointer an expected point value of 1.085 points; shots from inside the arc fell at about a 52% clip, giving those shots an expected value of 1.037 points. On the face of things, it would seem that, even though 3 out of every 10 attempts from the field were outside the arc, teams were leaving points on the floor by not shooting more threes.

If I had to guess, I'd say that we're seeing the continuation of a few trends: teams are hitting a higher percentage of their 3-point attempts, the number of those attempts is on the rise, and the rate at which 2-point attempts are made is pretty much holding steady. Graphically, it'd probably look something like this:I don't have to guess, though. I've got actual data to look at. It's a good thing, too, because, boy, would I be wrong. In fact, the ratio of three-point attempts to field goal attempts did rise pretty quickly from 1987 (when the three-point line was introduced) for the first decade of its existence, but it's leveled off since then, and even seems to be on the decline over the last four years. The success rate on three-point attempts has been steady since 1991. I'd have nailed the third part, though. The success rate inside the arc has been steady all along. Here's what the data actually looks like:

So, if the ACC numbers are at all reflective of the national trends, the argument that things have gotten too easy for long-range shooters seems to be bunk. While there was a decade-long adjustment period to the new rule as strategies evolved to take advantage of it, the game has stabilized over the second decade of the three point line's existence. Those who argue that the game is changing rapidly (implied: for the worse) don't have much of an empirical basis for their argument.

That's a good thing. Changing the rules of the game is an important undertaking, and it ought not be done for reactionary reasons. They should be made after careful thought both about the reasons for making the change and the consequences thereof.

1 comment:

JR said...

would like to see if those charts could have been created to your satisfaction using google spreadsheets... if it worked ok for you, you could publish it directly from the spreadsheet (using the range or the sheet which contains the chart).
I've ust noticed that you use Google spreadsheets for stats, so figured you may give the charting a try...