But Alex Green appears to be a fast healer
"I'm just blessed," Green said Saturday.
The second-year player has caught the eye of coaches and teammates since returning to the field for the start of the Packers' training camp, nine months after suffering a severe knee injury.
Green is being limited in the early part of camp, but coach Mike McCarthy has been pleased with how last year's third-round draft pick has performed after the first three days.
"We wouldn't have him out there if we felt that he didn't have the balance," McCarthy said. "And clearly passing the rehab part of it, we definitely take the high end (to caution), and it is a quicker recovery than probably some."
The Packers, who had their first practice in pads Saturday morning, are looking at a young group of backs to carry the load and take some pressure off quarterback Aaron Rodgers and a prolific passing attack.
Third-year player James Starks has the starting nod for now after splitting time in the backfield with Grant last season.
But Starks has been hindered by hamstring and ankle injuries the last two years, and his durability for being able to hold up for a full season has been called into question.
Brandon Saine, who did some good things in a situational role toward the end of last season as an undrafted rookie, also is in the mix for playing time.
Then there's Green, who took some satisfaction in the spring while he was recovering from his surgically repaired knee as the Packers took a pass on bringing back the 29-year-old Grant.
"It shows a lot of confidence in the running backs as a group," Green said. "It shows they have a little faith in us as well to carry the load that Ryan Grant left off. Now it's time for the young guys to step and play a big role."
Saying he's nearly 100 percent healthy again, Green is hopeful he can be a big contributor in Green Bay's offense this season.
Green averaged a nation-leading 8.2 yards per carry when he rushed for 1,199 yards and 18 touchdowns as a senior at Hawaii in 2010.
The Packers haven't had a 1,000-yard rusher since Grant ran for 1,253 yards in 2009 - his second straight season of eclipsing 1,200 yards rushing.
The 6-foot, 225-pound Green started to show glimpses of his powerful running style and big-play capabilities before he sustained a torn anterior cruciate ligament in his left knee last year. The injury happened when he was blocking on a kickoff return early in the Packers' win at Minnesota on Oct. 23.
Green went on injured reserve the next week and underwent surgery in mid-November.
At the time, expectations for Green to return to the football field by the end of July for training camp seemed unrealistic.
"I didn't set that goal until maybe March," Green said. "Obviously, when I first had surgery, my goal was to get my range back, be able to walk without crutches, things like that, just taking it a day at a time, a month at a time. As I got closer, I set my goals a little higher, to get back for training camp, get things rolling again."
The Packers are being cautious about not rushing an eager Green in his comeback.
"He's in a limited mode," McCarthy said. "He's on a rep count, so we're watching him. But I think he's put together three good practices."
Rodgers has been encouraged as well about Green's progress.
"It's fun to have another guy in the backfield to push James and Brandon and some of the young guys we've got," Rodgers said. "We know what kind of a player we have in Alex. It's just a matter of him staying healthy and making the most of his opportunities.
"I think what you saw last year was a guy who started a little slow in camp but really picked it up and everybody got real excited about him. And then he had the injury early in the season. So if he can stay healthy, I think he can be a good part of our offense."
Follow Associated Press writer Chris Jenkins on Twitter at twitter.com/ByChrisJenkins.