In 2011 the Titans defense was tasked with stopping another quick, mobile rookie quarterback in Cam Newton. The outcome was a 30-3 blowout win. This is in large part due to excellent game planning and perfectly executing the use of a spy.
A certain Instrument of War sums it up eloquently in a 2011 SI article:
"(Newton) holds the ball," said defensive tackle Jurrell Casey . "If a quarterback is going to hold onto the ball like that, we're going to get to him. We kept him in the pocket. He couldn't do anything but sit there. Having the spy on him meant he couldn't run, and our guys got to him."
Gray is a great mind to bring to the table against an inexperienced, mobile quarterback - he notched 28 interceptions during his career. If the responsibilities for the game plan against Geno Sunday pan out like they did in 2011 look for the secondary and linebackers to have a big day.
Here's the defensive stats from that game (per ESPN):
*(S) Chris Hope had an interception.
**(LB) Ayers recovered a fumble lost by TE Greg Olsen