When the Toronto Raptors’ Kawhi Leonard got the ball with 4.2 seconds left in a tied Game 7, it didn’t look like he’d get a good shot off. The Sixers had him guarded well. Ben Simmons forced him to the corner, and Joel Embiid made sure he wouldn’t get a great look. By the time Leonard released his jumper just before the buzzer, I was convinced the Sixers and Raptors were headed to overtime.
Even when it hit the rim, it looked short. Then it bounced and bounced and went down. Lucky-ass shot, I yelped. I texted it to people. I thought about it all night. I’m still thinking about it. How the hell did that go in?
Several Youtube videos now accuse the NBA of rigging the shot with magnets. Others on Reddit believe the same. To be fair, those sites attract the kind of people who would think pro basketball is controlled by magnets, and as with anything on the internet, it’s hard to tell where irony ends and sincerity begins. But it’s probably safe to say that at least some people have dealt with their frustration at Leonard’s shot by embracing conspiracy theories. (Did the league use a special ball made of metal on the last possession, or is the ball made of metal all the time and the rim magnets were activated for Kawhi’s shot? Just trying to figure out how this works.)
In order to debunk the magnetic rim theory and also cope with my own shock, I talked to two Philadelphia physicists to find out how the hell that ball went in.
First was Dr. Michael Vogeley, the associate department head for graduate studies at Drexel University’s physics department. “It went in because Leonard put an unusually high trajectory on the ball to get over Embiid’s outstretched arm,” Vogeley said in an email. “Usually a front rim shot clanks off or skips over. Here it bounces almost straight up.”
That tracks with what Leonard said after the game. “A couple possessions before that, I had the same kind of shot from three and ended up coming short,” the Raptors player said. “I just thought I had to put it up even higher than that.”
Vogeley went on to describe how the ball’s first bounce was nearly straight up: “The horizontal momentum towards the rim is almost exactly canceled by the effect of angular momentum of backspin when it hits the rim. There’s just enough momentum toward the rim center that, after three more bounces, it settles in.”
Bernd Surrow, the vice chair of Temple University’s physics department, also had an explanation. He said that while it’s tough to tell from video camera angles, it is “very likely” that the basketball went in due to “an increased level of friction during a reflection of the ball since the ball was spinning.”
“If an object bounces against a wall, the incident angle is identical to the reflection angle—assuming that any force from the object parallel to the wall is very small,” Surrow wrote in an email. “This can be changed if you give the ball a spin and allow to alter the force onto the ball parallel to the wall and therefore alter the trajectory after the collision leading to the fact that the incident angle would be different from the reflection angle.”
The backspin Leonard always puts on the ball as he shoots is important for his chances. “The guy has a great touch,” said Herb Magee, the legendary Philadelphia coach known as The Shot Doctor. “If you see the ball when he shoots it, he has perfect rotation every time. ... If you watch it, you see how long he held his follow-through. He was almost on the ground and he still held his right arm following through.” One of the things Magee teaches his players at Jefferson University is to complete the shot—basically, use an “exaggerated finish” to make sure your shot goes as straight as you want it.
Leonard always completes his shot. “He’s got beautiful form,” Magee said. “He shoots it with the guide hand all the time. His form doesn’t change if he’s on the move or if he’s just gearing up to take one on the dribble.” And so this shot over Embiid was just another shot for him. Magee agreed with the physicists: “The trajectory of the shot, because he had to go over Embiid, caused the ball to go maybe a bit higher than he normally shoots, and the ball came down on a descending arc. Then it caught the rim at the perfect spot and therefore the three or four bounces before it dropped through.”
Or, as Vogeley put it: “Luck, no. Physics, yes. And it helps just a little bit that Leonard is a lifetime almost 40 percent 3-point shooter.”
It wasn’t magnets. It wasn’t luck. It was a great shot from a great shooter in a huge playoff game. And now the science behind it will haunt me until the end of time.