His senior season in 2014, he won the Vern Smith Leadership Award, which is given to the best player in the MAC.

Overall, Mancz played for the Texans from 2015 to 2020, the Miami Dolphins in 2021, the Buffalo Bills in 2022, and the Minnesota Vikings in 2022.

[2] Mancz was also selected to play in the 2010 Ohio North-South All-Star Game and the 2010 Big 33 Classic.

[2][13][14] In July 2013, Mancz was named a nominee for the Allstate AFCA Good Works Team, which recognizes college football players for their community service.

[18] Mancz moved to center for the 2014 season to replace the recently graduated Zac Kerin.

[22][23][24] Also in July 2014, he was named a nominee for the Allstate AFCA Good Works Team for the second year in a row.

[26][21][27] Mancz then returned as a starter in the team's GoDaddy Bowl victory over Arkansas State.

[21][14][17] He also won Toledo football's Jim Nicholson Award, which is given to "the player contributing the most toward the success of the team".

[32][31][33] He was a finalist for the 2014 Wuerffel Trophy, which is given to the college football player "who combines outstanding community service with athletic and academic achievement".

[36][37][17] In May 2015, he received the MAC's Medal of Excellence Award, which is given annually to one male and one female member from the graduating class of each school in the conference.

[38] Mancz accepted an invitation to play in the 2015 East-West Shrine Game as part of the West Team.

[42][43] Mancz attended the 2015 NFL Combine but did not work out due to his January 2015 shoulder injury.

[47] Lance Zierlein of NFL.com said that "Based on Mancz's tape and history, one would have to expect that he will find a way to succeed in the league."

[60] With Martin returning from injury in 2017, Mancz began the season as the team's primary backup along the interior of the offensive line.

On September 18, Texans head coach Bill O'Brien stated that Mancz would remain the starting right guard even if Allen was healthy.

[63] However, he missed the Week 4 game against the Tennessee Titans on October 1 due to a knee injury.

[72] Due to an injury to Senio Kelemete, he started the Week 3 game against the New York Giants at left guard.

[1] Mancz suffered an ankle injury during the 2019 preseason that caused him to miss the first two games of the regular season.

[78] He started at right guard in Week 4 against the Carolina Panthers in place of the injured Zach Fulton, but suffered a concussion late in the game that caused him to miss the next five contests.

[79][78] Mancz then returned to play in the Texans' final seven games of the season, all in a non-starting role.

[91] He started the team's Week 4 game against the Indianapolis Colts after Michael Deiter was injured.

[78][93] He returned in Week 8 as the backup to Austin Reiter, playing two snaps on special teams.

[94][93] Mancz then started the Week 9 game against his former team, the Texans, but suffered an ankle injury and was replaced by Reiter after only playing nine snaps.

[104] On January 3, 2023, the Minnesota Vikings signed Mancz to the active roster after losing Brian O'Neill and Austin Schlottmann to injury.