Here is the R&A’s chief referee Grant Weir explaining the technicality of the rule that Bryson DeChambeau violated that resulted in the two-shot penalty.
“An improvement means ‘to alter one or more of the conditions affecting the stroke, so that the player gains a potential advantage for the stroke.’
“I would stress that this applies, even when the action is accidental as it was in Bryson’s case.
“The area of intended swing includes the entire area that might reasonably affect any part of the back swing, the downswing or the completion of the swing for the intended stroke, and importantly what the prohibited action here is that the player mustn’t move, bend or break any growing or attached natural object.
“A player is allowed to fairly take their stance by taking reasonable actions to get to the ball and take a stance if in some situations that improves the condition affecting the stroke, but when doing so, the player must take the least intrusive course of action to deal with the particular situation and is not entitled to a normal stance or swing.
“I would reiterate this rule applies even when there’s no intention to improve the area as was the case with Bryson.”

