The Dallas Cowboys made improving their putrid defense from a season ago , which ranked No. 30 overall in total defense. Dallas also had the worst pass defense in the league, which led to the team handing the keys to the defensive unit to Christian Parker . Parker is known for his ability to develop defensive backs, with All-Pros like Quinyon Mitchell, Cooper DeJean, Justin Simmons, and NFL Defensive Player of the Year Patrick Surtain II at his recent stops. That's why it comes as no surprise that the team brought in several defensive backs with ties to Parker and the new Cowboys defensive staff, like Jalen Thompson, PJ Locke, and Cobie Durant. Dallas also improved its pass rush before the NFL Draft, trading for Green Bay Packers Pro Bowler Rashan Gary. Despite all of the improvements, the Cowboys have plenty of doubters, with a new set of rankings placing the Dallas defense at No. 26 in the league .…