Citing a team source, Mike Freeman of Bleacher Report wrote on Wednesday that Gruden has "effectively replaced" general manager Reggie McKenzie mere months after rejoining the franchise on a 10-year, $100 million contract.
"Since joining the Raiders in January, Gruden has quietly consolidated power to the point where he's effectively the head coach, general manager, CEO and just about everything else," Freeman wrote. "No other coach in the NFL has this kind of power outside of (New England Patriots coach Bill) Belichick."
While Gruden and McKenzie are on record as saying they are in agreement on personnel moves, Freeman said that it is the former who has made nearly all of those decisions since returning to the team.
Speaking at the owners meetings in March, Raiders owner Mark Davis said that it was Gruden's team to build as he chose and that McKenzie was tasked with finding ways to make it happen.
"Jon's the head coach and he's going to be here a while, so it's important that he gets the players he wants and builds a team he wants to build," Davis said at the owner's meetings in March. "Reggie McKenzie is there with his staff to find the players and also keep the (salary) cap and everything else in order. ...
"He has built the team to where we are now and we're in pretty good shape with the (salary) cap and everything else. Now he has a head coach who's going to be running this thing for the next 10 years. His vision is going to be most important to building what type of team we've got."
The offseason has been a busy one for the Raiders, who have parted ways with wide receiver Michael Crabtree, punter Marquette King, wide receiver/kick returner Cordarelle Patterson and fullback Jamize Olawale among others.
Wide receiver Jordy Nelson essentially replaces the 30-year-old Crabtree, who was scheduled to make more than $7.7 million in base salary and bonuses in 2018.
Crabtree ultimately signed with the Baltimore Ravens.
Gruden initially noted that the presence of Crabtree was one of the reasons that he was interested in taking the Oakland job. But the availability of Nelson apparently changed his mind.
After missing the 2015 season because of a knee injury, Nelson had a big 2016 season for the Green Bay Packers with 97 receptions, 1,257 yards and a league-leading 14 touchdown catches.
Nelson's numbers declined significantly in 2017, when he had 53 catches for 482 yards and six touchdowns in 15 games.
Crabtree's numbers also went down in 2017. After having 89 receptions for 1,003 yards and eight touchdowns in 2016, he slipped to 58 catches, 618 yards and eight scores last season.
As for King, multiple media reports declared that Gruden had personality issues with the punter.
A second-team All-Pro selection in 2016, King ranked sixth in the NFL in punting average last season at 47.4 yards per kick.
King ultimately signed a three-year, $7 million contract with the AFC West rival Denver Broncos.
Gruden will see King and the Broncos on two occasions this season as he makes his return to the NFL since coaching his seventh and final season with the Tampa Bay Buccaneers in 2008.
He left the broadcast booth at ESPN to return to the franchise with which he spent his first four seasons as a head coach, posting a 38-26 regular-season record (40-28 overall) from 1998-2001 and guiding the team to two playoff berths, including appearances in the AFC Championship Game in his last two seasons.
Overall, Gruden is 95-81 in 11 regular seasons and 100-85 including the postseason.
Gruden succeeded coach Jack Del Rio, who was fired following a season-ending loss to the Los Angeles Chargers that capped a disappointing 6-10 campaign for the Raiders.
Davis said in January the hiring of Gruden culminated a six-year goal that started when his father, the late Al Davis, passed away in 2011.
Al Davis hired a 34-year-old Gruden to be the Raiders' head coach in 1998.