NAPA -- The Raiders have clearly reached a breaking point with Antonio Brown.
General manager Mike Mayock made that point clear during Sunday's final training-camp practice, which their superstar receiver did not attend over his longstanding helmet issue.
His quest to use a preferred Schutt Air Advantage helmet hit a snag on Saturday -- it failed an NFL test, per Pro Football Talk -- and he left camp in frustration.
The Raiders, and Mayock in particular, have been supportive of Brown's helmet preference. Going AWOL at this point, when he's healthy enough to practice fully for only the second time since dealing with frostbitten feet, is a point of contention for his employer.
"Antonio Brown is not here today, and here's the bottom line: he's upset about the helmet issue," Mayock said in a statement to reporters on hand Sunday in Napa. "We have supported that. We appreciate that. We have, at this point, exhausted all avenues of relief. From our perspective, it's time for him to be all-in or all-out.
"We're hoping he is back soon. We have 89 guys busting their tails. We are really excited about where this franchise is going, and we hope AB is going to be a big part of it starting Week 1 against Denver. End of story. No questions."
GM Mike Mayock issued a statement today regarding Antonio Brown. pic.twitter.com/5ueLsrOmid
Brown's helmet saga has gone on for months, because the Schutt Air Advantage helmet he has used in some form or another since high school was no longer permitted for use in NFL games. Only helmets certified by an independent safety body (NOCSAE) are eligible for use, and helmets over 10 years old are not eligible for certification.
According to an epic Twitter thread by NFL Network's Mike Silver, Brown has been so frustrated by an inability to use his preferred helmet, that he resorted to repainting a Schutt Air Advantage helmet brought in from outside the team when the Raiders wouldn't give him one.
Brown filed a grievance with the NFL and NFLPA to wear his preferred helmet, and an independent arbitrator formally ruled against him on Aug. 12.
Drew Rosenhaus, Brown's agent, said the following day that he believed a resolution was close thanks to a loophole in the certification rules. If Brown's camp could find a Schutt Air Advantage helmet less than 10 years old, they could re-condition it and get it re-certified.
Brown's camp crowd sourced the effort and acquired a few such models, though the NFL and NFLPA told Brown's representation that a newer version would have to be submitted to an independent lab for testing. Per a source, the helmet failed the test.
Brown's representatives were informed of the failed test on Saturday. After failing the test, the source said, the Schutt Air Advantage has now been placed on the list of helmets prohibited by the NFL.
Brown voiced his displeasure with that decision on social media, using language that will not be repeated here.
He left Raiders camp for a second time after receiving bad news about his helmet.
He came back Tuesday from his first absence, a 10-day stint in Florida, where Rosenhaus said he was gone only to receive treatment for frostbitten feet.
His private treatment ended before his Aug. 13 return to Napa, and Brown was healthy enough to run full speed in pre-game warm-ups before Thursday's exhibition in Arizona and participate fully in Saturday's walk-through practices.
He was supposed to practice fully on Sunday, for the first time since July 30, but left camp instead over this helmet news.
Brown's decision to leave amplified the Raiders' simmering frustration and prompted Mayock's statement, which drew a line in the sand.
[RELATED: AB's agent responds to Mayock's statement]
The Raiders traded third- and fifth-round picks to Pittsburgh for Brown, and subsequently reworked his contract to pay out $50 million over three seasons, including $30 million guaranteed.
Brown spoke after Thursday's preseason game and refuted a report that he would retire over this helmet issue.
"Why would I retire, man?" Brown said. "I have a beautiful career. I'm healthy. I love to play the game. Obviously, I inspire people with the way I play the game. I'm grateful to play the game. I'm excited to put it all on display, not only for my family but for these guys and our shared goals and everybody in the community who believes in me."
Brown said that before Saturday's news that his preferred helmet was prohibited. He and Rosenhaus have stated that they are willing to work within the system to find a helmet suitable for Brown to wear and feel safe playing in.
Brown has to decide his next course of action, whether or not to return to a team that has grown frustrated with his decision to leave the team over this issue, when there are plenty of certified helmets to choose from.