AP

Maybe now the Raiders have an idea why the Steelers traded a seven-time Pro Bowl receiver to them for such a low price.

Since he joined the Raiders, Antonio Brown has frustrated his new team by showing up late to numerous meetings and then often appearing unfocused in them, according to Michael Silver of the NFL. Brown is distracted by several tablets and his cell phone during meetings, checking his bank accounts and perusing Instagram, Silver reports.

That’s not even the biggest issue, though.

“The meeting thing isn’t that bad,” a source told Silver, “but the feet, helmet and going dark is an issue.”

Although a report earlier Friday said Brown is expected to rejoin the Raiders at training camp “sometime in the near future,” Brown’s issue with his helmet, which prompted him to file a grievance, apparently is what has kept him from Napa since late last week. It also caused him to storm out in protest during an organized team activity, according to Silver.

“He’s still freaking out about it,” an unnamed Raiders player told Silver. “He hasn’t been here for awhile, and no one knows where he’s at.”

Even before injuring his feet in a cryotherapy chamber, Brown’s resistance to complying with the NFL’s enhanced enforcement of helmet regulations “alarmed” coaches and teammates, per Silver. Team officials continually have told Brown he can’t wear his old helmet, which PFT has reported is just that — too old.

Brown continues to protest either verbally or by refusing to wear the new helmet.

“Honestly, the most insane thing I have ever heard,” a source told Silver. “I don’t know why it’s so important to him. It doesn’t make any sense.”

Brown, who has worn the same helmet for his entire career, initially was told in May that he would have to switch to a new helmet.

Brown, though, complained at the first organized team activity that he was being singled out. He stormed out of the facility, with team officials texting Brown video footage of Aaron Rodgers, who also has to change helmets, in an approved model.

Brown returned the following day and “acted like nothing had happened.” He practiced with the new helmet.

Days later, however, Brown again tried to wear his old helmet, which he repainted with colors

“approximating — but not completely mimicking — the Raiders’ silver-and-black design,” according to Silver. Brown complied, wearing a new model after team officials again told him his old helmet was banned.

The Raiders believed the issue was resolved when training camp began, but Brown arrived on the practice field with his old helmet.

Brown is expected to have a hearing on his grievance next week.

Meanwhile, whether it’s his feet or the helmet issue, Brown hasn’t participated in a full practice during camp and has taken part in only one of the Raiders’ 11 sessions.

Hard Knocks addressed none of the Brown saga during Tuesday’s premiere and made no mention of what is medically wrong with Brown’s feet, saying only the star receiver “is hobbled by injuries to his feet.”