The sides had until 4 p.m. ET on Monday to agree to a long-term contract. Since they couldn't, Avril will play the 2012 season on a one-year, $10.6 million franchise tag, but he'll become an unrestricted free agent after this season.
"I'm kind of disappointed that it didn't happen," Avril told the Detroit Free Press. "But obviously I'm not one of their top guys right now as far as getting a deal done."
"I'm not stressed out about anything," Avril also told the Lions' official website. "Business is business. It's not personal. My goal is to just keep getting better."