By Andrew Holleran The Denver Broncos are reportedly narrowing their head coaching candidates list and Dallas Cowboys defensive coordinator Dan Quinn might be emerging as the frontrunner. Quinn, who previously coached the Atlanta Falcons, making a Super Bowl, helped turn around the Cowboys defense in 2021. The Cowboys had multiple defensive stars in 2021, including rookie Micah Parsons and cornerback Trevon Diggs. Dallas was among the best in the league at forcing turnovers and making big plays on defense. Quinn might be one-and-done in Dallas, as he is emerging as a top candidate in Denver. B…