When Klint Kubiak agreed in February to become head coach of the Las Vegas Raiders, his father couldn’t resist offering a quip. After all, Gary Kubiak spent his entire NFL playing career as a quarterback with longtime AFC West rival Denver, was the Broncos’ offensive coordinator for 11 years and was head coach when they won their most recent Super Bowl in the 2015 season. “I said, ‘You know how hard this is for your dad after being a Bronco all these years and a Bronco for life,’’’ Gary told The Denver Gazette from his home in Plantersville, Texas. Obviously, though, the dad was ecastic when his son was named to coach the Raiders. The official announcement came Feb. 9, the day after Seattle, with Klint as offensive coordinator, defeated New England 29-13 in Super Bowl LX at Levi’s Stadium in Santa Clara, Calif. Seattle Seahawks offensive coordinator Klint Kubiak speaks during a news conference on Wednesday, Feb.…