Clowney made his professional debut on August 9, 2014, during the first preseason game against the Arizona Cardinals, where he made a tackle for a loss of 5 yards. During the second preseason game against the Atlanta Falcons, Clowney recorded his first professional sack where he sacked Matt Ryan. Before the third preseason game against the Denver Broncos, Clowney began to experience concussion-like symptoms after a helmet-to-helmet collision with tight end Jacob Tamme during dual practice and did not play for the rest of the preseason.
