The move to cut Arnette comes less than a week after No. 12 overall pick Henry Ruggs III was released following a fatal DUI crash. Authorities said Ruggs was driving 156 mph (251km/h) with a blood-alcohol level twice the legal limit in Nevada. He faces multiple felonies and jail time if convicted.
Mayock defended the Raiders' evaluation of character in the draft, saying the picks in the others years have been good character players and Arnette and Ruggs were aberrations.
"We found the risk acceptable after doing more homework on Arnette than anybody we've done in the years I've been here," Mayock said. "Obviously, we missed. That is 100% on me."
Arnette struggled when he played, dealing with injuries last season and then losing his starting job this year to Casey Hayward. Arnette was on injured reserve at the time of his release.
The two high-profile incidents with high draft picks raised questions about whether being in Las Vegas makes it more difficult on young players because of the temptations.
Mayock said the team does take the city into consideration when they look into acquiring players to determine how well they will fit but doesn't believe it's a major factor.
"We do have to be aware of Vegas. But my thing is in just about any mid- or big-sized city in the country, if you want to find trouble, you can find it," he said.
The 2020 draft class that featured two first-round picks and three third-rounders was being counted on to be part of the foundation of a rebuilding but instead will likely go down as one of the worst in franchise history.
The two first-round picks were cut midway through their second season. The first third-rounder, Lynn Bowden Jr, was traded in a pick swap deal last summer before playing a snap for the Raiders, and another third-rounder, Tanner Muse, was cut this summer having not played a snap.
The only remaining players are third-round receiver Bryan Edwards, fourth-round guard John Simpson and fourth-round cornerback Amik Robertson.
Edwards has 29 catches in 20 career games, Simpson has struggled playing in place of injured Richie Incognito and Robertson has been a healthy scratch the past two weeks after getting pulled early in a game at Denver. Robertson has started just twice in two seasons.
The Raiders did make one addition Monday, signing speedy veteran receiver DeSean Jackson. The 34-year-old Jackson was cut by the Rams last week. He had eight catches for 221 yards but will provide a needed deep threat with Ruggs gone.
The Raiders (5-3) are coming off a 23-16 loss to the New York Giants but are tied with the Chargers for first in the AFC West.