Boone, 36, lives in the Phoenix area and will work out this weekend with the Astros, his sixth big league team. If all continues to go well, he'll be activated on Tuesday when Major League rosters expand from 25 players to 40. How much he plays isn't material at this point. Whether he returns next season isn't on his scope.
Astros manger Cecil Cooper said he can't promise him any more than occasional at-bats, but so what? That's fine with Boone, who is just happy to be here.
"It takes a lot to do what he's done," Cooper said. "It wasn't an easy chore for him to go through what he has. It shows the kind of character, the kind of work ethic he has, determination, all of that, to get back. We're talking about a pretty major surgery, but here the guy is back in September."
Boone has recovered from reconstructive left knee surgery and more ups and downs in his 11-year career than entire franchises. But this comeback exceeds anyone's measure. Just to illustrate where he's recently been and where he currently is, Boone rolled up his black Astros T-shirt, revealing a pink, linier vertical scar where doctors cracked open his chest to perform surgery merely five months ago.
To correct a congenital condition that he learned about as a college student and only this past spring reached the danger zone, doctors replaced part of his aorta and repaired the defective valve.
"It kind of caught me off guard," Boone said. "I've known about it for a long time. I knew some day I'd have to do surgery. It was such a small part of my life. I went in for a checkup every year just to keep tabs on it. I didn't have any symptoms so to speak. It didn't affect my life any. Then all of a sudden, it was time. It was a bit sobering."
The procedure, clinically called bicuspid aortic valve aneurysm surgery, is named after Tyrone David, the Canadian surgeon, who invented it. Boone was on the operating table for hours and in recovery for weeks.
"The first week after surgery, it ain't no joke, it's the real deal," Boone said. "But then you feel yourself, you see yourself improving each day, each week, each month, literally getting better all the time. After they clear you to work out, to see your body respond and get better was kind of fun in a way. Now you try to keep your balance and not overdo it because you have a game to play.
"Not that I didn't have an appreciation of it before, but now I have a real appreciation for what it's like to play at the elite Major League level."
Boone, of course, has an epic Major League pedigree. His older brother, Bret, played 14 seasons and was an All-Star infielder. His father, Bob, was a top catcher for 19 seasons and won a World Series with the 1980 Phillies. His grandfather, Ray, played for 13 seasons and was a scout well into the later stages of a complete baseball life.
Aaron has been around the game since he was a kid and is comfortable in the baseball environs. The thought did cross his mind that the surgery could have ended all that.
"I love this game, but I'm not addicted to it," he said. "But once I was OK, I knew I was going to try [to make it back] and get myself in shape. Whatever it led to ... if it was over, that would have been OK, too."
Boone had been on a Minor League rehab assignment since Aug. 10 and had 15 at-bats for Double-A Corpus Christi before moving to Triple-A Round Rock, where he was 0-for-4 in two games. He's a .264 lifetime hitter with 126 homers and 555 RBIs.
As a member of the 2003 Yankees, he's most famously known for the walk-off, 11th-inning, Game 7 homer at Yankee Stadium against Boston that won the American League pennant. It has been a year-in, year-out struggle since then. Now he's on the precipice of another chance.
"I feel like I want to do this for me, for the Astros and for people I can help -- I feel like I owe it to them," Boone said. "I've had an awesome career. I've had a lot of ups, a lot of downs, a lot of injuries, a lot of comebacks. I made so many awesome friends in this game. The career I've had, I feel so blessed to have had it. I'm grateful for it."