Born on January 3, 1977 in North Little Rock, Arkansas, A.J. Burnett (Allan James Burnett) played for the Florida Marlins and Toronto Blue Jays over the course of his 8 year career. Burnett broke into the bigs on August 17, 1999 with the Florida Marlins, and put up a 4.79 ERA in 82.2 innings pitched in 2000, his rookie year.
In a seven-year career, Burnett has posted a 49-50 record with 753 strikeouts and a 3.73 ERA in 853.2 innings.
Burnett throws several different types of fastballs as well as a knuckle-curve. His fastball is regularly clocked in the high 90s and sometimes registers 100 mph on radar guns, which makes him one of the hardest-throwing starting pitchers in baseball.
Burnett was an eighth-round pick of the New York Mets in the 1995 amateur draft, but he was traded to the Marlins after the 1997 season when the Marlins dismantled their 1997 World Series championship roster. He was first called up to the Marlins from Class AA Portland in 1999, despite having a record of 6-12 and an ERA of 5.52 with Portland. He played parts of 1999 and 2000 with the Marlins; his first full regular season with the Marlins came in 2001, when he went 11-12 with an ERA of 4.05. On May 12, 2001, Burnett pitched a no-hitter but walked nine batters, which was a very unusual baseball feat. The 2002 season was probably his best to date (as of 2005); he complemented a 12-9 record that year with an ERA of 3.30 and a career-best 203 strikeouts.
Burnett was limited to four starts in 2003 before missing the rest of the season due to Tommy John surgery and thus did not play during the Marlins' World Series championship run. He returned in June 2004 and made 19 starts for the Marlins, going 7-6 with an ERA of 3.68. Even during 2004, his first season back from having the surgery, he was able to throw 100 mph. (He was shut down for most of September 2004 due to a less serious elbow injury.)
The 2005 season was Burnett's last with the Marlins before he became eligible for free agency. He said before the season that, like his former teammate Carl Pavano did in the 2004 offseason, he wanted to test the market rather than taking whatever new contract the Marlins gave him. Since he is likely to price himself out of the Marlins' budget, he was sought after by several other teams before the July 31 trade deadline, but he ended up not being traded. The Marlins will instead receive a supplementary first-round draft choice in 2006 if he signs with another team after becoming a free agent.
Burnett seemed to be pitching his best games of the season right around the trading deadline. After he took the loss in the Marlins' first game after the All-Star break, dropping his record to 5-6, he strung together seven consecutive wins. The last of those wins was on August 19, when he pitched eight shutout innings against the Los Angeles Dodgers. He then lost six consecutive decisions, including four losses in five starts (with an ERA in that span of 5.93) during the Marlins' failed wild-card chase in September, to close out the season with a 12-12 record despite a 3.44 ERA.
On September 27, 2005, Burnett was asked by the Marlins to leave the team. The request came a day after he made comments criticizing the organization:
- "We played scared. We managed scared. We coached scared," he told reporters following the Marlins' 5-3 loss at Turner Field. "I'm sick of it, man. It's depressing around here. A 3-0 ballgame, I give up one run and leave guys on base, it's like they expect us to mess up. And when we do, they chew us out. There is no positive, nothing around here for anybody."  
Marlins manager Jack McKeon called Burnett into his office and broke the news. Burnett shook his hand, gathered up his belongings, and left.
Burnett has since apologized, saying:
- "I have always been a very passionate player and person. I often wear my emotions on my sleeve, sometimes for better, sometimes for worse. I hope that my teammates always respect that of me, as I trust they know my commitment to winning. For those I've offended, I offer my most sincere apologies. " 
Because of his dismissal from the team, Burnett finished the season one inning short of receiving a $50,000 bonus for pitching 210 innings during the season; in addition, he was only two strikeouts shy of having his second 200-strikout season of his career. After Burnett's contract with the Marlins expired general manager Larry Beinfest the Marlins didn't attempt to re-sign him, which was unlikely to happen anyway, given Florida's financial constraints and the market for Burnett.
Incidentally, although in his remarks, Burnett criticized McKeon for not allowing the team's less experienced players to have much playing time, McKeon decided to let rookie Josh Johnson, a September callup from the Class AA Carolina Mudcats, make his first major-league start of his career on September 30, 2005. Previously, Burnett was scheduled to make his last start of the year at that game.
On the morning of December 6, 2005, at the Baseball Winter Meetings being held in Dallas, Texas, the Toronto Blue Jays signed A.J. Burnett to a five-year, $55 million deal.
The Toronto Blue Jays took a bit of a chance by signing Burnett to a five year deal due to his inability to stay healthy, and the 2006 season began with him going on the disabled list when a piece of scar tissue broke in his pitching arm. He was activated on April 15 and made a start against the Chicago White Sox, giving up four runs in six innings of work. In his next start against the Boston Red Sox, Burnett was removed from the game after only four innings due to soreness in his right arm. He was placed on the disabled list again as a precautionary measure even though he has no structural damage in his arm. There is currently no timetable for his return, but many suspect he will return in mid-June.
- Selected by New York Mets in the 8th round of the free-agent draft (June 1, 1995 - signed June 13, 1995).
- Traded by New York Mets with Jesus Sanchez and Robert Stratton to Florida Marlins in exchange for Al Leiter and Ralph Milliard (February 6, 1998).
- Granted free agency (October 27, 2005).
- Signed by Toronto Blue Jays (December 7, 2005).
- Led National League in shutouts in 2002.
- Pitched a 3-0 no-hitter against the San Diego Padres (at Jack Murphy Stadium, on May 12, 2001). He walked 9 batters in this game.
- Matched his own franchise single-game record by striking out 14 batters in a July 6, 2005, 12-inning 5-4 win against the Milwaukee Brewers, in which the Marlins struck out a team record 22 batters and retired 28 straight batters.
- Marlins' all-time leader in victories (49), complete games (14), shutouts (8), and strikeouts (753)
- Burnett plays in a rock band called Mad Ink with former Marlins teammate Tim Spooneybarger (who also had Tommy John surgery in 2003, but as of 2005 has not returned to playing). The group is so named because Burnett and Spooneybarger both sport many tattoos.
- A.J. uses a solid black baseball bat, and several of his bats have been customized as "Ozzy Osbourne" and "Marilyn Manson" models. The names of these rock singers are professionally etched in the barrels of the bats.