A right-handed pitcher out of Peabody, Mass., Allison has not pitched in professional ball since 2005, when he went 5-4 with a 4.18 ERA at low Class A Greensboro.
The Marlins' Minor League camp officially begins on Thursday in Jupiter, and Allison has already been on the backfields in drills with other players.
The 23-year-old has endured a number of off-field challenges ranging from substance abuse to arrests.
The Marlins placed Allison on the restricted list last July, meaning that he remained under club control but wasn't paid. Now he is in camp competing for a job, although it is too early to determine at which level he may end up.
Allison joins a stable of talented pitching prospects in the Marlins system. The team makes a strong commitment to drafting pitching, and Allison came out of Veterans Memorial High School in 2003 as a prep All-American.
But battles with addictions have repeatedly hindered his career, which is a total of 20 Minor League games.
Allison has thrown a total of 103 2/3 innings at the Class A level. In 2003 he made three starts in the Gulf Coast League, and after being out all of 2004, he started 17 games while logging 94 2/3 in 2005.
Nolasco impressive: The Ricky Nolasco of old is starting to emerge. It's a good sign for a team that now finds itself down a couple of potential starters.
On Wednesday night the right-hander tossed three scoreless innings and uncorked an effective curveball in a no-decision against the Cardinals.
Nolasco, 25, is striving to prove that he is healthy and ready to rejoin the rotation. He was part of the 2006 rotation that featured the only four rookies in Major League history to post double-digit victories in the same season.
Last year Nolasco was limited to just five games and 21 1/3 innings because of elbow inflammation.
"I feel pretty good at this point now," Nolasco said. "I am 100 percent healthy. That's all that matters to me right now. As long as I'm healthy, I'll looking to keep improving from here on out.
"All I can do is show them that I'm healthy, that I'm back to normal and that I can be effective in the big leagues like I was. I hope to prove that to them."
As a rookie in 2006, Nolasco was 11-11 with a 4.82 ERA in 35 games, with 22 starts.
The rotation took a blow this past week with Sergio Mitre hampered by right forearm tightness and Scott Olsen being scratched a start with left shoulder tendinitis.
Ramirez ready: Any worries that Hanley Ramirez's sore left ankle is a problem are being put to rest.
The 24-year-old shortstop played into the seventh inning on Wednesday night, when he went 2-for-3 with a walk. He blasted a three-run homer off Adam Wainwright, and he also singled off the Cardinals' ace.
In the seventh inning, Ramirez worked a walk against Randy Flores. At that point he was lifted for a pinch-runner.
Ramirez received a scare on Sunday when he jammed his left ankle in a collision at home plate with Cardinals catcher Yadier Molina. He sat out on Monday and was back in action on Tuesday.
Up next: On Thursday the Marlins and Cardinals hook up once again, but this time St. Louis will be the home team. Aaron Thompson (0-0, 4.50 ERA) takes the hill for Florida, while the Cardinals are going with Todd Wellemeyer (0-0, 0.00).
Joe Frisaro is a reporter for MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.