He played college football in Division I-AA for the Appalachian State Mountaineers, and was selected in the third round of the 1997 NFL draft by the Dallas Cowboys.
In order to meet academic requirements for College, Coakley attended Fork Union Military Academy's post-graduate program for one year, before accepting a scholarship to Appalachian State University.
While at Appalachian State University he grew bigger and was switched to linebacker, becoming the first two-time winner of the Buck Buchanan Awards, given each year to the nation's top Division I-AA defensive player.
Coakley was selected by the Dallas Cowboys in the third round (65th overall) of the 1997 NFL draft, after dropping because he was considered an undersized linebacker with a small college background.
In the 90's, the Cowboys organization felt they could find linebackers through the draft, without the need of paying a premium and adversely impacting the salary cap, so they allowed talented and productive players like Ken Norton Jr., Darrin Smith, Dixon Edwards, Robert Jones and Randall Godfrey, to leave via free agency, instead of signing them into long-term contracts.
Coakley is tied with Dennis Thurman and DaRon Bland for the club record for defensive touchdowns with five, coming on fumble (one) and interception (four) returns.
Coakley was a starter in 2005, registering 42 tackles, two sacks, and one interception in 12 games for the Rams, before suffering a season-ending fractured fibula and a dislocated ankle.