Now that getting back onto the field has become a reality, the 23-year-old right-hander also realizes that this is his last chance. There will be no more lifelines if this chance is wasted.
Once a highly regarded pitching prospect, Allison is in the process of rebuilding his life and baseball career.
Since being the 16th overall pick in the 2003 First-Year Player Draft, Allison has dealt with numerous struggles, ranging from addictions to arrests.
On Thursday, Allison was back in uniform on the first day Florida's Minor League camp opened. He's actually been in town about two weeks, and he was part of the workouts on the back fields on Wednesday.
"This is it. No more screwing around," Allison said. "It's time to grow up and that's how they put it."
Prior to being invited to camp, Allison was placed on the restricted list by the Marlins last July, meaning he was under club control but he wasn't been paid. He was also on the restricted lists in 2004 and '06.
It's been two years since he's pitched at the Minor League level, and his off-field issues have kept him out of three of the past four baseball seasons.
With a renewed outlook, Allison says he's been sober for 15 months. The Marlins have made their expectations of him clear.
"It's plain and simple, in black and white -- 'You're a grown man, if you want to play baseball, then do your thing,'" Allison said of the message the team gave him. "I'm here, I've been sober for a while, and I'm coming into camp at this point in my life, and it's a great feeling -- a real great feeling. There are a lot of people behind me."
Keeping his life in order and making baseball part of it are his goals.
In 2005, Allison appeared in 17 games at low Class A Greensboro. He was 5-4 with a 4.18 ERA. Since being drafted out of Veterans Memorial High School in Massachusetts, Allison has appeared in a total of 20 professional games, and his career record is 5-6 (3.91 ERA).
"I'm a grown man now," he said. "I've got to be who I was meant to be, and that's playing baseball. And [I have to] move along in the process and live a good life -- a normal life.
A touching moment came on Wednesday when he walked into the Minor League clubhouse and saw a No. 93 jersey with "Allison" on the back.
"They could have given me No. 100 and I wouldn't have given a [darn]," he said. "To see my name on that jersey, and to get out there and do what I was meant to do, it was a weird feeling, but it was a good feeling at the same time. It's good to be out here. I have a lot of people to thank in this organization, people who have stood by me."
Among those who reached out to the troubled pitcher were team performance enhancement physician Jeff Fishbein, owner Jeffrey Loria, president of baseball operations Larry Beinfest and vice president of player development and scouting Jim Fleming.
"When I wasn't playing baseball, I tried a lot of things, working," Allison said. "I did all right, but being here is different. This is what I know. This is what I did best, and [I'm] trying hard to get to the big leagues at some point in my life. Hopefully, that would come. Right now, I have to crawl before I walk. That's where I'm at right now."
Allison threw a bullpen session on Thursday, and in a couple of days, he is expected to throw live batting practice. He threw off the mound seven times in the weeks leading up to camp.
Chances are he will start off at one of the low-level Class A teams when the season starts.
"They [Marlins] saw something in me that I didn't see in myself for a long time," Allison said. "I finally found it myself. I feel a lot different than I did a few years ago. It's different now. I have almost two years under my belt now, being clean, and it's a great feeling."
What happened in the past, his many battles with addictions and legal issues, are behind him. Allison doesn't talk much about what went wrong, and he says he is focused on the future.
"When I talk to anybody, they know not to really dabble into that unless they're a personal friend, or whatnot," he said. "I just want to focus on baseball, and do my best.
"I still have a long ways to go, but I have a lot more motivation now. I have something to prove to myself, and to everybody else, but to myself, first and foremost. It's about staying healthy for me, taking it easy out here and working hard. It's baseball."
Joe Frisaro is a reporter for MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.