As a freshman, McManis was named to Sporting News' freshman All-Big Ten team after recording 21 tackles, breaking up six passes and making one interception. As a sophomore, he became a full-time starter on defense, and recorded 75 tackles, 6.5 tackles-for-loss, seven pass break-ups, and one interception. As a junior, he recorded 53 tackles, broke up 14 passes and had two interceptions. As a senior, he earned first-team All-Big Ten honors after he set career highs in interceptions with five, and recorded 37 tackles, 1.5 tackles-for-loss, and broke up 12 passes. He finished his collegiate career with 201 tackles, eight tackles-for-loss, 39 pass break-ups, and nine interceptions.
McManis was drafted by the Houston Texans in the fifth round of the 2010 NFL Draft. He signed a four-year, $1.982 million contract with the Texans on May 27.
Chicago Bears
On August 31, 2012, McManis was traded to the Chicago Bears for fullback Tyler Clutts. In Week 9 against the Tennessee Titans, McManis blocked Brett Kern's punt, which was recovered by former Northwestern teammate Corey Wootton, who returned the blocked punt for a touchdown. McManis was eventually named the NFC Special TeamsPlayer of the Week. McManis was placed on injured reserve on December 11. In the 2015 season, McManis had 11 special-teams tackles, which led the team. On March 10, 2016, McManis was re-signed by the Bears to a two-year contract. On March 22, 2018, McManis signed a two-year contract to remain with the Bears. Since 2012, McManis has been Chicago's special teams ace, spending time as a captain while making 80 tackles in that time entering the 2018 season. In Week 3 against the Arizona Cardinals, McManis recorded his first interception since 2010 off Sam Bradford's pass to Chad Williams. Later in the season, he became the Bears' starting nickelback after Bryce Callahan suffered a season-ending foot injury. In week 5 of the 2019 season against the Oakland Raiders, McManis forced a fumble on Trevor Davis on the goal line in the 24–21 loss. He was placed on injured reserve on November 30, 2019. McManis signed a one-year extension with the Bears on April 16, 2020. As of the 2020 season, McManis is the longest tenured Bears player, having played under four different coaching regimes dating back to Lovie Smith in 2012.
