The NFL decided at its owners' meetings today that a defender will get a radio speaker in his helmet beginning next season.
The rule allows the defense to have one player on the field with a radio link to the coaches, similar to the quarterback on offense. Only one player on the field can have the defensive radio link and no more than two defensive players can have the radio total.
I blogged about this issue earlier on Lake Affected.
The defensive substitution issue came up again, but I don't see it as a big deal. I'm sure there are defensive players that are on the field all the time that can have the radio and call the plays. And if there is a substitution, make the defensive call the old-fashioned way. The offense has the same problem if they substitute.
If Steelers quarterback Ben Roethlisberger came off the field because (now former) receiver Antawn Randle El was going to play quarterback on a gadget play, then someone else had to get the play signed in to the huddle. It didn't happen often, and I think defenses will find their trend is the same.
The important thing is the temptation for teams to steal defensive signals has been all but eliminated.