In 2011, he won a starting position and set a school record with 18 passes defended, while also finishing the season fifth on the team with 69 tackles, and two interceptions.

In his senior season, he intercepted a career-high five passes while adding 75 tackles, earning himself a first-team All-SEC selection.

[6] Throughout training camp, Gaines competed to be a backup cornerback against Brandon McGee, Quinton Pointer, Marcus Roberson, Greg Reid, and Darren Woodard.

[7] Head coach Jeff Fisher named Gaines the third cornerback on the Rams' depth chart, behind Janoris Jenkins and Trumaine Johnson.

[8] He started 15 games his rookie season in 2014, recording 70 tackles, 14 passes defensed and two interceptions, earning him a spot on the PFWA All-Rookie Team.

Gaines signed with the Cleveland Browns on March 23, 2018, reuniting with former Rams defensive coordinator Gregg Williams.

[13] In Week 4 against the Oakland Raiders, Gaines intercepted quarterback Derek Carr and made five tackles in a 45–42 overtime loss.

[18] On August 2, 2020, Bills general manager Brandon Beane announced that Gaines would opt out of the 2020 season due to the COVID-19 pandemic.