The Phillies have given Adams a two-year, $12 million deal that could go as high as $18.5 million if the pitcher's vesting option based on appearances kicks in for the 2015 season.
"There is no question that there is some risk involved," Amaro said during a news conference at Citizens Bank Park.
It's a risk that revolves around a condition known as thoracic outlet syndrome (TOS). The former Texas Rangers pitcher gave a descriptive account of the debilitating condition that dogged him for almost the entire 2012 season.
"Last year was a struggle for me," Adams said. "The TOS was something that kicked in in early April. I didn't know what was happening. I thought I was just having some shoulder discomfort issues. The majority of the season I battled not having the same stuff I had previously."
Adams finished the season with a 3.27 ERA, respectable for most relievers but uncharacteristically high for him. In fact, it's the overall track record that made Adams so appealing to the Phillies and a lot of other teams. Adams said he turned down more guaranteed money from another National League East team just so he could pitch with the Phillies.
"As a group, we talked to our people about the TOS and how that might affect him short term and long term, but I think ultimately we feel comfortable . . . with the procedure and the follow-up information that we got," Amaro said. "While there is some risk to it, it probably was a good risk. This is a guy who can solidify our bullpen."
In 243 career appearances against National League teams, Adams has a 1.97 ERA with 257 strikeouts and 74 walks in 251 innings. His ERA since the 2009 season is 1.84, so his credentials are far superior to what the Phillies rolled the dice on with Baez, Contreras, and Qualls.
The only scary thing about Adams is the TOS condition, which made his 2012 season a nightmare.
"By the end of the year, it really caught up to me," he said. "My arm felt like it weighed five or six pounds more than it normally did. The ball felt like it weighed three pounds."
Adams surrendered three home runs in a five-batter span in his final appearance of the season against Oakland and did not pitch in the final week, when the Rangers fell out of first place during a series in Oakland. He had allowed just one home run in his first 60 appearances of the season.
"My last outing, I felt like I was pitching a shot put," Adams said. "The toughest part was the mental part. I was trying to fix my mechanics, and I was trying to fix everything."
Mental relief was provided by his Texas teammate Matt Harrison.
"He told me I was going to feel great after [surgery]," Adams said.
Harrison had surgery for the condition in 2009 and has recovered to become one of the best starting pitchers in the American League.
Adams had his surgery, which requires the removal of a rib, in mid-October and said the rehab process has gone well. He expects to be ready for the start of spring training. The Phillies sent Charley Kerfeld to watch him throw earlier this month, and the special assistant to the GM came away satisfied with what he saw.
"It's the first rib, which is below the clavicle," Adams said. "You have a main artery and a nerve that runs through there, so when you start squeezing those, that nerve starts shooting pain through your body. I was having headaches constantly for three weeks. My [trapezius] was hurting, my pec, the middle of my back was hurt. I was having some numbness and tingling in my bicep and forearm, and it was something that was pretty bad."
The Phillies are risking $12 million that Adams' turbulent 2012 will be followed by good health and the same quality pitching he has provided for the Padres and Rangers over the last five years.
Contact Bob Brookover at firstname.lastname@example.org, or follow on Twitter @brookob.