Basketball is still adjusting to the three-point field goal

Rules are an important part of the design of marketplaces, and also of games and competitive sports. And it can take time for participants to adjust to changes in the rules and settle into a new equilibrium. Here's some history of 3-point rules in Wikipedia.

The WSJ has the story of the growth of 3-point baskets in professional basketball:

The One Number That Explains the NBA’s 3-Point Revolution--No team had ever taken 40% of its shots as 3-pointers until 2017. Now half the league is doing it.    By Ben Cohen

"When the NBA slapped a 3-point line on the court and declared certain shots worth more than other shots, the single most consequential rule change in modern sports, it would take years for basketball teams to realize they had different incentives. Slowly at first, and then with astonishing speed, they shot more and more 3-pointers. But for almost four decades, there was a limit. No team attempted 40% of its shots as threes. 

"Then it happened in 2017. It happened again in 2018—but with two teams above the 40% threshold. That number would balloon to five in 2019 and nine in 2020. 

"But what’s happening this season is a rapid acceleration of a trend that has reshaped the game. There are currently 15 teams with 3-point rates above 40%. Half the league is now doing something that until recently no team in the history of the league had ever done.

...

"At last year’s MIT Sloan Sports Analytics Conference, an event where many bold predictions about the future of basketball have turned out to be prescient, some NBA team executives felt the 3-point boom was only beginning. 

“The people entering the league today started playing still before this 3-point explosion,” said Mike Zarren, the Boston Celtics’ assistant general manager. “There’s a lot of kids now who are learning to shoot a lot of threes—so there ought to be more good shooters coming.” 

...

"One shot is worth 50% more than another shot a few inches away. In the NBA, a ruthless, zero-sum industry with billions of dollars at stake, that’s incredible value. It’s the type of glaring inefficiency that teams would have to be foolish to ignore. 

“I don’t think we’ve reached the upper limit yet,” said Haralabos Voulgaris, the Mavericks’ director of quantitative research and development. “I think when you start getting into around 60 to 65% 3-point rate, that’s probably where you’re getting toward more diminishing returns.”