[citation needed] After signing with the Marlins in 2003, the team did not want to strain Allison's arm after a fairly long high school season and he only appeared in 3 games with the Gulf Coast Marlins of the Gulf Coast League for rookies.

Allison was rumored to have entered a substance abuse treatment program and was forced to forfeit a portion of his signing bonus money.

Allison was briefly promoted to the Double-A Jacksonville Suns for a spot start on August 5, 2009, where he allowed one hit over 5 innings and earned the win.

In a February 2012 article by Peter Gammons, Allison was quoted as stating that he would most likely be retiring from professional baseball.

[5] Allison stated that he heard a pop in his elbow three years prior but ignored it, the injury would require surgery and an extended rehabilitation period.

Allison's personal struggles have been well documented, most specifically in a Boston Globe two-part special article that ran in 2004.

Both battled intense drug addiction, Hamilton with cocaine and crack, Allison with heroin and oxycodone.

ESPN's Peter Gammons mentioned the similarities between the two players during his commentary at the 2008 MLB All Star Game.

[8] Starting in 2011, Allison worked as a pitching instructor and head coach at the Show Baseball Academy in Lawrence, Massachusetts.

[9] In 2015, Allison left the Show in order to join the North East Hurricanes and play ball in Salem, New Hampshire.

In addition to coaching, Allison gives speeches to students and shares his experience and struggles in order to promote sobriety.