As many of you know, the New York Jets are being scrutinized because assistant coach Sal Alosi was caught tripping a Miami Dolphins player on the sideline during a game last weekend. The Jets at first downplayed the incident -- apologizing and moving on -- but they later discovered that Alosi instructed others to intentionally form a wall on the sideline to block special teamers from using the sidelines.
The NFL found out what was going on and got involved sending a letter to every team instructing them to appoint a "get-back coach", according to the (other) AP.
So if Westhoff has been doing this for a while or the Patriots did it, I imagine someone on the Chiefs coaching staff has heard of this tactic. It hasn't been going on in KC and this letter assures us that it won't be in the future.