Defensive help priority for Raiders as they ready for NFL combine

The franchise that once specialized in top-10 draft busts — JaMarcus Russell, Michael Huff and Darrius Heyward-Bey, oh my — recently has converted its draft-day layups.

In 2014, Raiders general manager Reggie McKenzie used the No. 5 pick on linebacker Khalil Mack, who was a first-team All-Pro in his second year.

In 2015, McKenzie used the No. 4 selection on wide receiver Amari Cooper, who had a 1,000-yard season as a rookie.

The lack of first-round whiffs helps explain last year’s 7-9 record, a four-win improvement over 2014. Still, the bad old days aren’t quite over — Cooper was 7 years old when the Raiders last had a winning season — and McKenzie could help put them over the hump by…