“Iowa State Shoots Too Many Threes!”

It seems to be a common misconception for many, many fans.  They see a team shooting a lot of threes and their instincts kick in that it is far, far too many to attempt.  Granted, every three pointer taken isn’t necessarily a good shot but it also isn’t necessarily a bad shot.
Consider the chart above.  It accounts for every conference game played to date by the Cyclones.  It shows the 3FGM, 3FGA, 2FGM, and 2FGA and the corresponding percentage of success fore each in each game.
What I have also done is calculated the effective field goal percentage for the three point attempts alone.  That looks like this: (1.5 x 3FGM) / 3FGA
The point is to give credit for the true value of the three point shot because it is worth one extra point.  For clarification, the 2FG% is the same as if you would try to calculate the effective field goal percentage for just two point shots.
The next thing I did was turned it into a color coded mess.  Every game that is highlighted in green the Cyclones shot a better effective field goal percentage from behind the arc than inside (most every case was by more than 15% but the away game with Kansas was 48.21% to 38.46%).
In orange is every game where the Cyclone’s effective field goal percentage from three was within ten percentage points (usually much less) of their two point field goal percentage.  Finally, there were just two games—both against Texas Tech—where the Cyclones outshot their eFG% from three point land than the percentage they shot from two by more than 10%.
One important note is that the randomness of these occurrences appears to have zero correlation to whether the game was won or lost.
Some may be concerned that an excess of attempts from three isn’t aggressive enough and that it will not force opponents into fouls.  While that is a traditional thought, at least this year’s 85 Big 12 conference games do not support it.
Using the correlation coefficient to compare a team’s attempted threes to opponent’s fouls (all 170 data points) the rating comes back as -0.19. While the fouls tend to decrease as a team’s three point attempts increase, the correlation is not statistically even moderate (would require -0.3 on the scale from -1 to 1).
All shots are not created equal and all three point attempts are not inherently good and neither are all two point attempts.  It may seem easy to become disgruntled with missed three pointers, but the fact of the matter for this year’s Cyclone basketball team is that they are a far more efficient scoring team from outside the arc than inside the arc.
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2 Responses to “Iowa State Shoots Too Many Threes!”

  1. Keep in mind that an equally effective eFG for 3 point shots has to be higher than the eFG for 2 point shots because the odds on post-miss outcomes for 2 point shots have a higher expected point value. For example, a missed 2 point shot has a much higher chance to be scored on a putback.

    • Anonymous says:

      I don’t know that I agree with that. You’d have to look at rebounds. A miss from 3 (longer rebound) might favor the shooting team.

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