I’d read recently on Kevin Pelton’s Statistical Analysis Primer that “Effective Field-Goal Percentage was invented by current L.A. Clippers Coach Mike Dunleavy.”
Dunleavy as statistical innovator came as some surprise because the Clippers aren’t regarded as an organization on the vanguard of advanced analytics. By Dunleavy’s own admission, he wasn’t looking to glean any rarefied knowledge about the basketball universe when he came up with effective field goal percentage. He was just trying to negotiate a fair contract in the latter half of his playing career.
The way Dunleavy tells the story, this was in the early 80s, when Dunleavey was negotiating his own contract.
“I’m doing my own deal with this general manager,” Dunleavy said. “I asked for whatever I asked for and he offered me like half of that.”
Dunleavy declined to say which team or general manager he was negotiating with, but remembered the conversation with the executive vividly.
“He says, ‘your numbers are good, but they aren’t great,'” Dunleavy said. “So I went away and started thinking about it. I look at the other guys getting paid. And I’m thinking, ‘I’m making these 3s, which are one-and-a-half times a regular shot.'”
Dunleavy became a 3-point specialist a few years into his career. With San Antonio in 1982-83 he led the NBA in both shots made beyond the arc (67) and 3-point percentage (34.5%). But the added value of a 3-pointer isn’t factored into basic field goal percentage.
“So I took all my 3-point field goals divided by two, and added those to my amount of field goals,” Dunleavy said. “I went to the guy and said, ‘Okay, I shoot 47 percent. But if I shot 52 or 53 percent, what would I be worth?'”
Dunleavy put what he referred to as his “effective field goal percentage” figures on the table, and the two sides ultimately came to an agreement.
“I didn’t get all of what I asked for,” Dunleavy said. “But I got more.”