The NBA has told referees to call more offensive fouls this season when players push off defenders with their free arm, SB Nation reported. Analysts say the change could hurt some of the league's best scorers, especially Shai Gilgeous-Alexander.

Ball handlers often use their "off arm," the one without the ball, to create space from a defender. SB Nation said the move dates back at least to Michael Jordan's famous shot in the 1998 Finals, but it has gotten more extreme.

The league released a video explaining the new rules, narrated by its head of referee training, Monty McCutchen, FanSided reported.

Referees have been told to look for the "Four F's," FanSided said: feeling, firming, force and full extension. A player may use his off arm to "feel" a defender or to "firm up" in front of him. But referees should call an offensive foul if the arm hits the defender with force or is fully extended to gain an edge.

Gilgeous-Alexander is not shown in the league's video, SB Nation noted. But the writer said the Oklahoma City Thunder star is the player most likely to be watched. He has won two MVP awards in a row, and SB Nation said his use of the off arm took his game "to the next level."

FanSided said the change could make it harder for him to win a third straight MVP. Only Bill Russell, Wilt Chamberlain and Larry Bird have done that.

Early preseason games show referees are making the call. FanSided pointed to a play in which Toronto's Scottie Barnes was called for pushing off Klay Thompson.

The league is also cracking down on push-offs by players setting screens, SB Nation said. It noted that past points of emphasis have sometimes faded after the first few weeks.

What we know: Referees will call more off-arm push-offs this season.
What we don't: Whether the crackdown will last all season.