"You get hit by Haloti Ngata, you will get a concussion," nose guard Ma'ake Kemeatu said.
Cassel was on the ground for several minutes before wobbling off the field with trainers.
It was a devastating hit as the 6-foot-4, 350-pounder had a full head of steam when he crashed into Cassel.
"I knew I hit him hard," Ngata said. "I didn't think I hit him hard enough to take him out."
Before kickoff, an airplane circled the stadium with a banner calling for Cassel to be benched and for general manager Scott Pioli to be fired.
Fans cheered when Cassel got hurt, seemingly overjoyed to see backup quarterback Brady Quinn enter the game.
"That's not cool," Ngata said. "He's your quarterback. For them to cheer for him being hurt, that's just not cool."
After the game, Cassel was visibly upset.
"It was sad to see the fans cheer for somebody getting hurt," Kemoeatu said. "It's a horrible situaiton. I hope he's fine."
Chiefs offensive tackle Eric Winston went on a rant after the game where he criticized the fans for taking joy in Cassel's pain.
"We are athletes, we are not gladiators,” Winston told Kansas City reporters. “This isn’t the Roman Colisseum. People pay their hard-earned money to come in here. I believe they can boo, they can cheer, they can do whatever they want. But when you cheer somebody getting knocked out, I don’t care who it is, and it just so happened to be Matt Cassel, it’s sickening. It’s 100 percent sickening. I’ve been in some rough times on some rough teams. I’ve never been so embarrassed in my life to play football than at that moment right there.”
"Matt Cassel hasn’t done anything to you people, hasn’t done anything to the media writers who kill him, hasn’t done anything wrong to the people that come out here and cheer him. 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 got 70,000 people cheering If you’re one of those people who were out there cheering, or even smiled, when he got knocked out, I just want everyone to know it’s sickening and disgusting.”
Cassel completed only 9 of 15 passes for 92 yards, no touchdowns and two interceptions for a 38.1 quarterback rating.
The Chiefs' coaches showed little faith in him, even running the football in third-and-long situations.
"None, it was surprising becuase he's a very capable quarterback," cornerback Cary Williams said. "I don't know if he lost confidence in himself. He's under a lot of scrutiny from fans and media as well. It's not our job to worry about that. It's not our problem."
Asked about the Chiefs' unwillingness to rely on Cassel, cornerback Lardarius Webb replied: "I don't know what was going on with that. I'm not going to complain about that."Copyright © 2015, The Baltimore Sun