Kollar joined the Houston Texans in 2009 and spent six years there, including his first five years as assistant head coach/defensive line. During his tenure with the Texans, the team ranked eighth in the NFL in total defense (329 .4 ypg) and third in the league in opponent third-down percentage (35.9). Kollar’s unit adjusted to the defense’s transition to a 3-4 scheme in 2011 under Houston Defensive Coordinator Wade Phillips. The Texans went on to post the third-largest defensive turnaround (-91.2 ypg) in NFL history in 2011. Defensive ends Mario Williams, Antonio Smith and J.J. Watt combined for five Pro Bowls playing for Kollar in Houston.