The reason for the depth against GT was that they were literally on an island. They couldn't allow themselves to get sucked up into all that misdirection etc going on because it's chaotic. Example, the QB options right, pitches the ball to the RB, who then throws to a wide open WR because the CB came up for run support. He has to stay back and ensure that the play is past the LOS before he comes up. They were 10 yds deep and the WR still got behind them a few times. But, their 1st option is their deep 3rd of the field.