Seattle Seahawks cornerback Richard Sherman spoke out against the NFL’s new helmet rules Sunday in a post on Twitter.

The NFL’s new rules prevents players from leading with their helmets in an attempt to promote safety in the game and have been heavily criticized by players since its creation in March.

The intention of the rule is to “take the head out of the game,” League commissioner Roger Goodell explained in March.

In a series of tweets Sunday, Sherman criticized the rule, explaining to those who created it that it is “impossible” to run full speed and lead with anything other than the head while trying to tackle a moving target.

“There is no ‘make adjustment’ to the way you tackle,” Sherman wrote on Twitter. “Even in a perfect form tackle the body is led by the head. The rule is idiotic And should be dismissed immediately. When you watch rugby players tackle they are still lead by their head. Will be flag football soon.”

Sherman’s comment is in response to several moments in preseason games over the weekend in which defensive players were called for penalties in what appeared to be clean plays.