Conrad Dobler, a three-time Pro Bowler, died Monday at the age of 72, the Arizona Cardinals confirmed. 

"Our hearts go out to the family, friends and former teammates of Conrad Dobler," the posted on social media. 

Dobler was a key member of the "Cardiac Cards" of the then-St. Louis Cardinals from 1972-1977, where he was also named a second-team All-Pro. Dobler played in the trenches as a left and right guard, under Don Coryell, who was posthumously inducted into the Pro Football Hall of Fame on Thursday. 

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Conrad Dobler #66 of the St. Louis Cardinals watches the action from the sidelines during an NFL football game circa 1977. Dobler played for the Cardinals from 1972-77. (Focus on Sport/Getty Images)

"He was the kind of tough, physical and fierce player that you love to line up with as a teammate and hate to line up against as an opponent. On the field, Conrad was a big reason for the success of the Cardiac Cards of the 1970s,'' Cardinals owner Michael Bidwill said in a statement.

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Dobler spent six seasons with the Cardinals before playing for the New Orleans Saints and Buffalo Bills prior to his retirement in 1981. He played 129 career games, starting all but four of them. 

But many who remember Dobler think about things that certainly wouldn’t fly in today’s league. 

Jethro Pugh #75 of the Dallas Cowboys rushes up against Conrad Dobler #66 of the St. Louis Cardinals during an NFL football game December 3, 1972 at Busch Stadium in St. Louis, Missouri. Pugh played for the Cowboys from 1965-78. (Focus on Sport/Getty Images)

Dobler was notorious for using any means necessary to block for his quarterback and running back, and these tactics were violations of the league rules. It’s why some consider him to be the dirtiest player in history, as he would’ve received multiple ejections in today’s game. 

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Dobler also relished getting in defensive linemen’s heads, visibly confronting them in between plays including "Mean" Joe Greene. 

Conrad Dobler #66 of the St. Louis Cardinals watches the action from the bench during an NFL football game circa 1977. Dobler played for the Cardinals from 1972-77. (Focus on Sport/Getty Images)

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The Cardinals drafted Dobler in the fifth round of the 192 NFL Draft out of Wyoming.