Meanwhile, the 27-year-old Gamel faces another surgery and second straight summer of rehab.
"He was pretty good when I talked to him earlier today, but it had to crush you," manager Ron Roenicke said. "You go through a long rehab period -- which isn't fun, it's lonely, it's hard work, boring at times -- and now to think you have to go through it all again. It's pretty rough."
But the injury is not considered career-threatening, assistant GM Gord Ash said.
"Clearly it's a setback, and a tough thing as much mentally as physically for a guy to spend eight months rehabbing and then be told he's got to start all over again," Ash said. "I do think he has youth on his side. It's not like this is a 38-year-old guy and he knows this is the end of the line."
Brewers officials were stunned by the severity of Gamel's setback. He rehabbed the original injury throughout the 2012 season and received positive check-ups both at the Brewers' late-January "On Deck" event in Milwaukee and in a physical exam last week.
But Gamel reported discomfort after stretching and hitting during the team's first full-squad workout on Saturday, and head physician William Raasch detected enough give in Gamel's knee to order an MRI scan. It revealed the bad news.
"It's a tear of the middle portion of the repair, which as Dr. Raasch explains to me is unusual," Ash said. "There are failures -- I guess 10 percent seems to be the historical number. But of those failures, they're mostly at either end, and this is in the middle, which is unusual."
Gamel has a history of terribly timed injuries. In 2010, a torn muscle behind his throwing shoulder cost him a shot at the Opening Day roster, and in 2011 it was a rib cage strain. Last year, he got his big break as the Brewers' replacement for the departed Prince Fielder, but tore his ACL after banging into a low wall at Petco Park in San Diego on May 1.
Now Gamel will have to endure another repair and another year of rehabilitation, though the Brewers don't expect this latest setback to threaten his career.
"There's been numbers and numbers of athletes go through this," Brewers head athletic trainer Dan Wright said, with Ash pointing to former Brewers infielder Tony Graffanino.
Gamel was not available Monday to discuss his setback but will find a clubhouse full of moral support when he returns to Maryvale Baseball Park on Tuesday. Among the friendly faces will be Hart, who has already extended an offer for Gamel to move in with Hart and his family for the remainder of Spring Training. Hart has a guest house available.
"I'll try to help him out as much as I can," Hart said. "It stinks, because I was pumping him up. Hopefully I'll be here a long time, but I was trying to be realistic [about Hart's impending free agency] and telling him, 'Look, I might not be here and this might be your one month to showcase it.' [Now] I can just hug him and hope it works out."
The two have been providing support for almost a year now. It was Hart who stepped in to cover first base after the Brewers lost Gamel last season, and it was Gamel who was supposed to be stepping in for Hart to start this year. Since reporting to Arizona, Gamel had been driving 20 minutes out of his way each morning and afternoon to drive Hart, who is still on crutches, to and from Maryvale Baseball Park.
Now that Gamel is incapacitated, what will they do?
"My wife might be chauffeuring two guys around for a couple of days," Hart said. "It's tough luck. I hope his spirits are high -- I know they're not now -- but if everyone supports him, at least he'll have more confidence going forward."