Jimmy Johnson makes a very good point about the formations and sets that Gibbs is running plays from.
Gibbs runs most of his running plays from the Singleback Big set (1 runningback, 1 tight end, 1 H-back, 2 WRs), usually with the WRs in a "twins" look on the H-back side. From this look, he has three basic plays that he runs, with the most basic being a simple off-tackle play with
zone blocking. Off of that, he runs the counter and the cutback, which are designed to take advantage of overpursuit by the defense. Since he runs all of these plays from the same formation most of the time (occasionally throwing in some motion from the slot or the H-back), it becomes increasingly easier for the defense to diagnose the plays as the game goes on, particularly if they have studied their film-- as the Browns clearly did. It simply becomes a matter of looking for visual cues at that point.
The point that Jimmy Johnson is trying to make is that in his first tenure, Gibbs always ran the same basic plays, but he ran them from so many different looks, with pre-snap shifts and motion, that it was very difficult for the defense to key on anything. This time around, with the shorter playclock, Gibbs is having a hard time getting the play in on time, and Brunell simply doesn't have enough time to get the offense to the line of scrimmage and shuffle through a series of pre-snap shifts and motion. Gibbs has also tried to eliminate illegal motion and illegal formation penalties caused by receivers (cough, cough-- Gardner!-- ahem) lining up incorrectly. This makes Gibbs's offense much more predictable and readable for the defense, causing plays for negative yardage, and it's a primary factor in the offense's inability to move the ball consistently.