Every golfer has heard it. You miss a breaking putt on the low side and your playing partner says, "That's the amateur side." Pros miss high. Amateurs miss low.
But WHY? A 2024 study in PLOS ONE by Hasegawa, Okada, and Fujii dug into this with some clever methodology, and the answer is more interesting than "read the green better."
Amateurs underestimated how much the break actually was. They started the ball too low, and the ball broke below the cup. Classic amateur side.
But it gets worse for amateurs. Not only did they tend to underread the amount of break, but whatever break they did think was there, they tended to setup and line the face up with even less break than they thought was there. It's not just that they couldn't see the break. They couldn't correctly act on whatever they did see. To put this in a simple example: The putt has 24 inches of ACTUAL break. The amateurs saw 12 inches of break, but when they lined up they were only playing 8 inches of break.
This is from Lou Stagner's newsletter which you can find here - Lou Stagner's Newsletter