[James Neil]

Originally posted by Bob M.
REPLY: An NFL friend of mine told me what they look for when a player is suspect for holding at the point of attack: Look for the blockee to make an “unathletic move.”.... And the big one…look for the blockee to “lose his legs.” Let’s have some more discussion about this.

Good stuff Bob. I was taught this philosophy in Personal Touch Camp
One example of “lose his legs” you want to watch for during passing situations, is when you see the on-rushing defensive lineman falling down on top of the retreating blocker in a very “unathletic move.”
More then likely the offence lineman has slipped his hands underneath the front of the sholder pads of the onrushing defenceive lineman, or gather up a bunch of his jersey and just fallen backward. This one I was told has to be flagged.
I was also told that holding will become easer to see if I keep my focus on my keys. As an Umpire I’m to focus on the snapper and the two adjoining players. Keep these players in your line of sight forming a triangle as you move to the line of scrimmage. In other words “fish in your own pond” and you’ll bag the big one.