Shell abruptly called practice to a halt on the last day of double sessions, ending the workout a good 50 minutes early. He called the team together in the center of the field, spoke to them in a voice loud of enough to be heard but not deciphered from the sidelines, then banished them to the field house that houses the locker room and weight room.
There was none of the usual banter that accompanies the end of practice. The Raiders jogged off together silently, changed, then slowly filed out of the field house and back to their hotel rooms at the Napa Valley Marriott.
Shell was keeping the disciplinary action in-house both on the day it occurred and on the day after.
"Practice is over," Shell said. "When you're out here, you've got to work."
The following day, after a practice that met his expectations, Shell said of the shortened workout, "I just gave them the day off, that's all."
So why was Shell so upset?
Either no one was really sure, or no one was willing to tell. Many Raiders waved off questions from reporters after it happened, and even the next day wanted to avoid the subject.
"Art Shell wanted us to regroup, I guess," normally talkative safety Stuart Schweigert said. "I probably shouldn't talk to anyone about it. I don't want to get in trouble from anyone."
Defensive tackle Warren Sapp said Shell's message was loud and clear.
"It was a statement that was pretty well felt throughout the whole team, I would expect, and if it wasn't, then we're in trouble," Sapp said.
Sapp, who said he had never been ordered off the field as a high school, college or professional player, would not go into detail.
"Whatever Art gave you is what you guys can go on," Sapp said. "I'm just a soldier in this army. I'm taking orders, I'm not giving any."
Quarterback Aaron Brooks said that Shell did everyone a favor by cutting short practice.
"I think we kind of needed to step away from it and refocus ourselves," Brooks said. "It was like hitting that wall. You want a break. You have five pre-season games, we just want to go play an opponent. It was much better today."
He liked Shell's method of quiet but stern insistence rather than having someone screaming like a drill sergeant.
"At a time like that you don't want to overemphasize yelling," Brooks said. "All the fatigue, mental fatigue, physical fatigue, it sets in. A lot of mistakes will happen. A lot of sluggishness. It's something you have to monitor."