The 47-year-old Schwartz went 29-51 with the Lions, and in 2011 he led Detroit to its first winning record since 2000.
Schwartz informed the players of the decision during a team meeting.
"It was a tough meeting," Raiola said. "He should be proud. He took a job that nobody wanted and he should be proud of where he brought this team from. We were in the cellar, we were in that cave, that tunnel that there is no light. We were the worst team in history. It's crazy."
This season particularly stung for Lions players because of the way it ended. For Raiola, one of the few Lions still with the club from the team's 0-16 season, the way this one ended was worse.
"To me, it feels worse because we had a chance to have a home playoff game and it just feels like we didn't take advantage of that opportunity," Raiola said. "It feels like everything that needed to happen or could have went our way, went our way. And we did not take advantage of those opportunities."
Yet this season, many of the same issues repeated themselves, along with the same excuses from players and coaches about being "one play away."
But the Lions were never able to make that play, which led to Schwartz's eventual firing Monday.
"Just feel bad for a guy like that who is very passionate, has given a lot to the organization and got a lot out of this organization," wide receiver Nate Burleson said. "But it's a business, and when you don't get the results that the organization wants and what the people want, then decisions like this have to be made. So I understand it, but it's tough to deal with."
Information from The Associated Press was used in this report.