Entering 2015, the Tennessee Titans needed a complete reset following a dismal 2-14 campaign. Hope arrived with Marcus Mariota, selected second overall in the draft, alongside free-agent additions Brian Orakpo, Perrish Cox, Da'Norris Searcy, and Harry Douglas. Yet early optimism evaporated under head coach Ken Whisenhunt, who was fired after a sluggish 1-6 start. Interim head coach Mike Mularkey took over, but Tennessee managed only a 3-13 record, finishing fourth in the AFC South and missing the postseason for a seventh straight year. The bottom-tier finish secured the number one overall pick in the upcoming draft while prompting general manager Ruston Webster's dismissal.

Tennessee's offense sputtered, ranking 28th in scoring with 299 points (18.7 ppg) and 30th in total yards at 4,988. Mariota flashed star potential across 12 starts, completing 62.2 percent of his passes for 2,818 yards, 19 touchdowns, and 10 interceptions while adding 252 rushing yards and two scores. When injury sidelined Mariota, backup Zach Mettenberger struggled in four starts, throwing for 935 yards, four touchdowns, and seven interceptions. Running back Antonio Andrews led a quiet ground game with 520 rushing yards. The single offense highlight was veteran tight end Delanie Walker, who earned Pro Bowl honors after catching 94 passes for 1,088 yards and six touchdowns.

Defensive coordinator Ray Horton and assistant Dick LeBeau directed a unit that finished 12th in total yards allowed at 5,475, including a pass defense that ranked seventh by yielding 3,678 yards. However, red-zone vulnerabilities and an offense continually turning the ball over led to 423 points allowed (26.4 ppg), ranking 27th in scoring defense. Defensive tackle Jurrell Casey anchored the front, recording seven sacks and 11 tackles for loss to earn Pro Bowl selection alongside newcomer Brian Orakpo, who also logged seven sacks. Inside linebackers Avery Williamson and Wesley Woodyard stabilized the interior, compiling 102 and 87 tackles respectively, while safety Michael Griffin posted 101 tackles.

The season began with fireworks in Week 1, as Mariota threw four first-half touchdown passes during a 42-14 victory over Tampa Bay. That excitement vanished in a six-game skid that cost Whisenhunt his job. Mularkey won his interim debut in Week 9, with Mariota returning to throw a game-winning touchdown in a 34-28 overtime triumph over New Orleans. Week 13 delivered another highlight against Jacksonville when Mariota ripped off an 87-yard touchdown run in a 42-39 thriller. However, four straight December losses sealed a grueling autumn.

Missing the playoffs again underscored Tennessee's ongoing transition, yet 2015 established the cornerstone for future success through Mariota's promise and Delanie Walker's career-best season. Individual accolades for Pro Bowlers Casey and Walker offered bright spots amid team struggles. By finishing 3-13, Tennessee secured the top draft selection, granting management critical leverage to rebuild the roster and establish a physical culture that would eventually reshape the franchise.