[9] Throughout training camp, Casey competed against Tony Brown, Shaun Smith, Jason Jones, Jovan Haye, Karl Klug, and Sen'Derrick Marks for the starting defensive tackle job.

[12] On October 9, 2011, Casey recorded four combined tackles and made his first career sack on quarterback Ben Roethlisberger in the Titans lost to the Pittsburgh Steelers by a score of 38–17.

[13][14][15] Casey returned in 2012 and competed against Shaun Smith, Sen'Derrick Marks, and Karl Klug to maintain his starting defensive tackle position.

[17] In Week 9, he collected five combined tackles, sacked quarterback Jay Cutler, and caused a forced fumble in a 51–20 loss to the Chicago Bears.

[18] On December 30, 2012, Casey made five solo tackles and recorded his third sack of the season on Chad Henne during the Titans' 38–20 victory over the Jacksonville Jaguars.

[20] Throughout training camp, he competed with Sammie Lee Hill, Karl Klug, and Mike Martin for the role as starting defensive tackle after Sen'Derrick Marks departed for the Jacksonville Jaguars in free agency.

[21] He started in the Tennessee Titans' season-opener at the Pittsburgh Steelers and recorded three solo tackles and sacked Ben Roethliserger twice during a 16–9 victory.

[22] On November 3, 2013, Casey recorded a season-high six solo tackles and had two sacks on St. Louis Rams' quarterback Kellen Clemens in Tennessee's 28–21 victory.

[24] In Week 15, Casey recorded a season-high nine combined tackles and had 1+1⁄2 sacks on Arizona Cardinals' quarterback Carson Palmer in the Titans' 37–34 overtime loss.

[31] On September 14, 2014, Casey made two solo tackles and two sacks on quarterback Tony Romo as the Titans lost to the Dallas Cowboys by a score of 26–10.

During a Week 6 matchup against the Jacksonville Jaguars, Casey collected a season-high nine combined tackles and made two sacks on quarterback Blake Bortles during a 16–14 victory.

[34] Casey returned as the de facto starting right defensive tackle in his second consecutive season under head coach Ken Whisenhunt.

[37] On January 31, 2016, Casey appeared in the Pro Bowl for Deion Sanders' team and recorded two combined tackles, a pass deflection, and an interception in their 49–27 victory.

On October 9, he recorded two solo tackles and two sacks on quarterback Ryan Tannehill as the Titans defeated the Miami Dolphins by a score of 30–17.

[40] On December 20, 2016, Casey was named to the 2017 Pro Bowl, along with teammates DeMarco Murray, Brian Orakpo, Taylor Lewan, and Delanie Walker.

[42] On January 1, 2017, Casey collected six combined tackles, deflected a pass, and made two sacks on quarterback Brock Osweiler as the Titans defeated the Houston Texans by a score of 24–17.

Three weeks later against the Los Angeles Chargers, he recovered a fumble forced by teammate Wesley Woodyard on running back Melvin Gordon on the goal line late in the fourth quarter which sealed a 23–20 victory.

In the divisional round of the playoffs against the Baltimore Ravens, he sacked quarterback Lamar Jackson twice, one of which was a strip-sack that was recovered by teammate Jeffery Simmons.

[65] Casey and teammate Wesley Woodyard coach a women's flag football team composed of wives and significant others of Titans players.