The Bills placed Merriman on injured reserve Saturday because of a nagging Achilles' tendon injury, culminating a tumultuous year for the one-time feared linebacker.
At the time, Merriman also was nursing a strained Achilles' tendon. In his first practice with the Bills on Nov. 10, he lasted just 15 minutes before re-injuring it.
The Bills also placed linebacker Keith Ellison on injured reserve Saturday. Ellison couldn't practice all week because of an unspecified knee injury.
"We felt it was still going to be some time before Shawne and Keith were healthy enough to return to the field, and we certainly were not going to have them return to action until they were physically ready to do so," Bills general manager Buddy Nix said, according to the team's official website. "Knowing that we needed the roster spots, we felt this was the best move for our team and it's also best for both players. The most important thing at this point is for them to get healthy, and this gives them that opportunity."
To fill the two open roster spots, the Bills promoted wide receiver Naaman Roosevelt and linebacker Thomas Williams to the 53-man roster from the practice squad.
The following Wednesday, Merriman walked onto the practice field for the first time with his new team, but that's when things went awry. During a harmless-looking individual drill, he backpedaled, then pivoted to his left before pulling up and hopping on one leg.
Merriman immediately pulled down his right sock and limped to the sideline, where a trainer spent a few minutes checking the linebacker's ankle. Merriman then consulted head trainer Bud Carpenter at midfield before being escorted to the Bills' fieldhouse, where the team's training room is located.
Merriman sounded resigned about his situation when asked about it Friday.
"It's coming along, but it's still the same situation it was a few weeks ago. Just wait and see what happens," Merriman said after practice, according to the Buffalo News. "My main thing is just to get it healthy. It's been there for a year. I haven't had many other problems other than that. It's been there constantly -- on and off -- for a year now, and I never really had a chance to take care of it. I've been pretty healthy the last couple of years -- other than that. It's unfortunate, but I have to get it taken care of."
Nicknamed "Lights Out" for his aggressive and hard-hitting style, Merriman has 43.5 sacks in his 60-game NFL career. But his production has substantially dropped over the past three seasons, largely because of nagging injuries, including reconstructive knee surgery that forced him to miss most of 2008.
Since the start of the '08 campaign, Merriman has just four sacks in 18 games.
Merriman received a four-game suspension in 2006 after testing positive for steroids. He blamed the positive test on a tainted supplement, which he never identified.
Merriman also brought unwanted attention off the field after being arrested just before the 2009 season when reality television star Tila Tequila accused him of battery and false imprisonment at his suburban San Diego home. No charges were filed, and Merriman and Tequila settled dueling lawsuits.
The Associated Press contributed to this report.