He accepted a football scholarship from the University of South Florida. As a freshman, he appeared in 12 games, making 8 tackles, 4 tackles for loss, one quarterback pressure, one pass defensed and a fumble recovery. As a sophomore he started 9 games at defensive tackle, tallying 32 tackles, 3.5 tackles for loss, 3 sacks, one quarterback pressure and a forced fumble. As a junior he started 11 games as part of a defense that ranked 19th in the nation in scoring, posting 25 tackles, 1.5 sacks, 3 quarterback pressures, 5 tackles for loss and a forced fumble. As a senior, he started 13 games, collecting 24 tackles, 3 sacks, 5 quarterback pressures and 4.5 tackles for loss.
Professional career
Carolina Panthers
McClain was selected by the Carolina Panthers in the third round of the 2011 NFL Draft. As a rookie, he started 12 games at defensive tackle registering 20 tackles, a sack and a fumble recovery, before being placed on the injured reserve list with a left knee injury on December 6. He was released on September 2, 2012.
McClain signed with the New England Patriots on September 26, 2012. He was waived on October 2, after being active for one game and not recording any statistics.
Houston Texans
McClain signed with the Houston Texans as a free agent on October 29, 2012. He played in 16 games and finished with a career-high 21 tackles and a fumble recovery.
Dallas Cowboys
McClain signed as a free agent with the Dallas Cowboys on March 12, 2014. Although he looked strong and was taking advantage of the added work as Henry Melton recovered from knee surgery during off-season workouts, a high-ankle sprain he suffered in training camp affected his momentum. He played 13 games in a reserve role and finished with 20 tackles, 7 quarterback pressures, one sack and a forced fumble. His best game came against the Washington Redskins, notching 4 tackles, one sack and a forced fumble. In 2015, he missed time during training camp with a bone bruise and hamstring injuries. He registered 4 tackles in the first two regular-season games, before being placed on the injured reserve list with a sprained big toe injury on September 22. In 2016, he was able to earn a starting position over new free agent addition Cedric Thornton. He started in 15 games mostly at the three technique position and was considered the bestdefensive lineman on the team according to the media and observers. In the season opener against the New York Giants he had 5 tackles. His best game came against the Cincinnati Bengals, when he registered 6 tackles, 1.5 sacks and 3 quarterback hurries. He did not play in the last game to rest an ankle injury he suffered against the Detroit Lions and be ready for the playoffs. He finished the season with 41 tackles, 2.5 sacks, 8 quarterback pressures and 2 forced fumbles.
Washington Redskins
On March 10, 2017, McClain signed a four-year contract with the Washington Redskins. He started 2 out of 12 games at defensive end in the team's 3-4 defense, after being passed on the depth chart by Stacy McGee. He registered 20 tackles, 2 sacks and one fumble recovery. He missed weeks 12 through 15 with a toe injury he suffered against the New Orleans Saints. He was released on April 30, 2018.
Atlanta Falcons
On May 11, 2018, McClain signed with the Atlanta Falcons.
Arizona Cardinals
On May 22, 2019, McClain signed with the Arizona Cardinals. On August 26, 2019, McClain was released by the Cardinals.
