ORCHARD PARK, N.Y. -- Forget extending Shawne Merriman any belated birthday wishes. For someone who turned 28 last week, the Buffalo Bills defensive end suddenly feels as if he's actually turning back the clock.
"A year older? I'm like Benjamin Button, man," Merriman said with a smile, referring to the fictional character who aged in reverse. "I'm going backward."
On the field, Merriman took a big step forward Thursday by fully taking part in his first team practice since having season-ending surgery to repair a partially torn right Achilles tendon in November.
Merriman's presence at the Bills second voluntary minicamp session came two days after he received a clean bill of health from James Andrews, the doctor who performed the operation.
Confident he's put his injury troubles behind, the NFL's 2005 defensive rookie of the year believes he's finally in a position to regain the form that earned him three Pro Bowl selections and the nickname "Lights Out" as having been one of the league's most dominating pass rushers.
"I feel young," Merriman said. "Anybody that will get a chance to watch me this year will see I'm moving around as I did when I came into the league."
The opportunity to finally prove himself couldn't come soon enough for a player whose future was being questioned, and who is entering the final year of his contract with Buffalo.
He ran out of second chances in San Diego two years ago, when the Chargers released him after five-plus seasons. And Merriman's barely made a dent in Buffalo, since the Bills took a chance by acquiring him off waivers in November 2010.
He finished the 2010 season on injured reserve after aggravating his Achilles tendon injury in his first practice with the Bills. And Merriman had nine tackles and two sacks in starting only five games last year with Buffalo before electing to have season-ending surgery.
The injuries -- he also had minor shoulder surgery in November -- have taken a toll on Merriman's production. He's managed just two sacks in his past three seasons, after registering 39½ in his first three.
Merriman's recovery has been on schedule, and he spent much of the offseason working out under the watchful eye of doctors and trainers in Florida.
The next step came Thursday in a non-contact practice that was closed to reporters. Though he's easing himself back, Merriman is pleased with how practice went and how much better his Achilles feels.
"To go out there and do everything now, and get that push-off, get that explosion, things that made me the player I am in this league, it feels great," he said.
That's a switch from before, when he was slowed by injuries.
"I was in a position where I couldn't go out and perform, I couldn't go out and do the things I do best," Merriman said. "I couldn't explode."
Merriman has the opportunity to be a valuable addition to a defense that's been rebuilt this offseason with a focus on pressuring opposing quarterbacks. With Buffalo switching back to a 4-3 style of defense, Merriman will be part of a veteran core of defensive ends headed by Mario Williams, the team's high-profile free agent signing, and rounded out by Chris Kelsay and Mark Anderson, another free agent addition.
"I know why they brought me here, and I know what I'm capable of doing for my team," Merriman said. "The additions we made with Mario and Mark and all the other guys that came in, it's going to be huge year. But we don't want it to be a huge year on paper. We want to go out and who people it's going to be a huge year on game day."
Merriman has already set some personal goals, but is keeping them to himself. He'd prefer his performance do the talking.
"I'm really ready to go out there and show what kind of year I'm ready to have," Merriman said. "The type of work that I've put in this offseason, my body's ready to have that kind of year."
The Bills signed undrafted rookie free agent DB Isaiah Green out of Fresno State on Thursday. Listed at 5-foot-10 and 180 pounds, Green was credited with 94 tackles and 14 passes defensed in 46 career games. ... To make room on the roster, Buffalo released LB Garrick Williams. ... The Bills close this week's voluntary minicamp session with a practice Friday.