Holding or not

[Theisey]

The difference is that the low block or clip at the LOS last for a split second or less. I.e. until the ball leaves the zone.
Those defensive linemen still have a fair chance to continue the persuit despite.

To allow holding behind the line because the offensive linemen are not as big or as fast as his defensive opponent would dramatically change the game. I have no intention to check this out, but I recall some stats that said that NFL O-lineman are bigger than D-lineman. They may not be as fast, but for the most part they are bigger. So learn how to block is the counterpoint.

Holding behind the line, especially on pass plays should be called every time.