to begin the regular season. They started alongside inside linebackers Brian Cushing and Joe Mays. Mercilus started in the season-opener at the San Diego Chargers and recorded five solo tackles and one sack during a 31–28 victory. In Week 4, he collected six combined tackles and recorded a season-high 2.5 sacks as the Texans lost to the Seattle Seahawks 23–20. During Week 12, Mercilus collected a season-high six solo tackles during a 13–6 loss to the Jacksonville Jaguars. On December 6, 2013, the Houston Texans fired head coach Gary Kubiak after they fell to a 2–11 record. Defensive coordinator Wade Phillips was named the interim head coach for the rest of the season. Mercilus finished his second professional season with 47 combined tackles (33 solo) and seven sacks in 16 games and starts. 2014 season On January 3, 2014, the Texans hired Penn State head coach Bill O’Brien. Defensive coordinator Romeo Crennel retained Mercilus as a starting outside linebacker. Mercilus started alongside Jadeveon Clowney and inside linebackers Brian Cushing and Jeff Tarpinian. During Week 9, Mercilus collected a season-high nine combined tackles and made two sacks during a 31–21 loss to the Philadelphia Eagles. He was inactive for the Texans’ Week 15 loss at the Tennessee Titans due to a back injury. Mercilus finished the 2014 season with 50 combined tackles (31 solo) and five sacks in 15 games and 13 starts. 2015 season On May 4, 2015, the Texans signed Mercilus to a four-year, $26 million contract extension with $10.68 million guaranteed and a signing bonus of $5.25 million. He entered training camp slated as a starting outside linebacker, but saw some minor competition from John Simon after he impressed coaches while filling in for Jadeveon Clowney during camp. Head coach Bill O’Brien retained Mercilus and Clowney as the starting outside linebackers to begin the regular season in 2015. During Week 8, Mercilus collected a season-high seven combined tackles and recorded 3.5 sacks as the Texans defeated the Tennessee Titans by a score of 20–6. In the regular-season finale, he recorded five combined tackles and tied his season-high of 3.5 sacks during a 30–6 victory over the Jacksonville Jaguars. Mercilus finished the 2015 season with 52 combined tackles (32 solo), a career-high 12 sacks, and two pass deflections in 16 games and 10 starts. The Texans finished atop the AFC South with a 9–7 record and earned a wildcard