Should the play be called dead?

[ABoselli]

Jerry Markbreit had this question last week or the week before.

He stated (I'll paraphrase) that as soon as a player gives himself up by going to one knee, he is down. He stated that he cannot be hit and that a lot of players will touch him to make sure he's 'down by contact' but that this action is not necessary. He further stated that the player will often yell "I'm down" or words to that effect when they do it.

Sliding by a QB is a different deal as the ball is dead where he begins his slide and he can't be hit. A lot of times you'll see him get hit a little by a player that was in the process of attempting a tackle but it is usually incidental stuff. The ball is dead, though, on each play.