KANSAS CITY, Mo. -- Chiefs quarterback Matt Cassel lay flat on his back in the fourth quarter, staring up at the sky, where just a few hours earlier an airplane towed a banner calling for him to be benched.
This wasn't how anybody expected his time as Kansas City's starting quarterback to end.
Cassel was eventually helped to his feet and walked off the field on his own, going up the tunnel and into the locker room with what later was diagnosed with a concussion, a source told ESPN NFL Insider Adam Schefter.
Fans have been calling for Cassel to be benched for several weeks, and certainly have been dissatisfied with his performance for longer than that. He was booed during a celebrity softball game across the parking lot at Kauffman Stadium during Major League Baseball's All-Star festivities.
The fact that some of them cheered when he got hurt didn't sit well with the Chiefs.
"It's 100 percent sickening," right tackle Eric Winston said. "If he's not the best quarterback, he's not the best quarterback, and that's OK. But he's a person. And he got knocked out in a game and we've got 70,000 people cheering that he got knocked out."
Cassel never returned, leaving Brady Quinn to try to rally Kansas City to a victory over the Baltimore Ravens on Sunday.
It's unclear how long Cassel will be out, but at this point every indication is that Quinn will be the starter when the Chiefs head to Tampa Bay next weekend.
Quinn led the Chiefs to a field goal on his only series, but the Chiefs defense couldn't get the ball back in the closing minutes, allowing the Ravens to hold on for a 9-6 victory.
"If we will play like that going forward, we give ourselves a chance to win the game," Chiefs coach Romeo Crennel said. "We had a chance in this game. So even though I'm disappointed in the loss, the way the team played, we played much better overall football."
That wasn't necessarily the case for Cassel, who threw for just 92 yards and was picked off twice along with being credited for two lost fumbles.
His day finally ended when Ravens defensive tackle Haloti Ngata got to him in the fourth quarter, hitting him just as he released a completed pass to Jamaal Charles out of the backfield.
Charles, who had 140 yards rushing in the game, said "it's just not right," when asked about the fans' reaction to Cassel's injury.
Information from ESPN NFL Insider Adam Schefter and The Associated Press was used in this report.