Alameda, CA (SportsNetwork.com) - Jack Del Rio is an NFL head coach again.

According to multiple reports, Del Rio has reached an agreement with the Oakland Raiders, meaning the 51-year-old will move from one of the NFL's best teams over the past three seasons to one of its worst.

NFL.com reported that Del Rio will receive a four-year contract. He will become the Raiders' seventh full-time head coach since 2004.

Del Rio joins the Raiders after two seasons as defensive coordinator for AFC West rival Denver. The Broncos had the NFL's third-ranked defense during the regular season, a jump of 11 places from Del Rio's first year at the helm.

He was head coach of the Jacksonville Jaguars from 2003 until he was fired in 2011 near the end of his ninth season. The Jaguars were 68-71 under Del Rio, making the playoffs twice.

He takes over on a full-time basis for Dennis Allen, who was fired by Oakland in September after the Raiders lost their first four games. Allen was 8-28 in two-plus season at the helm.

Former Miami Dolphins head coach Tony Sparano served as interim coach for the Raiders after Allen's firing, leading them to a 3-9 mark the rest of the way.

The 3-13 record was Oakland's worst since a 2-14 mark in 2006. The Raiders haven't had a winning season since 2002, the year they won 11 games on the way to a Super Bowl appearance under Bill Callahan.

Before his stint as Jaguars head coach, Del Rio was defensive coordinator for the Carolina Panthers in 2002 after spending time on the coaching staffs of the New Orleans Saints and Baltimore Ravens.

In 2013, he served as interim head coach of the Broncos for four games while John Fox recovered from heart surgery.