Oviedo was born in Bonao in the Dominican Republic. At age 17, Oviedo assumed the identity of his 16-year-old best friend, Leo Nunez, in order to receive a more lucrative contract. In 2011, Marlins reliever Edward Mujica, a close friend of Oviedo's, said that "t 17 years old, you maybe lose $100,000 or $150,000 when you sign . And if you're like 18, you might sign for $5,000 and maybe they give you an opportunity."
He had his contract purchased by the big league club on May 9, 2005, and made his major league debut on the same day. Along with teammates Ambiorix Burgos and Andrew Sisco, they were the first trio of rookie pitchers in major league history to throw at least 50.0 innings each without making a start. Oviedo finished the 2005 season with a 3–2 record and a 7.55 ERA in 41 games. In 2006, Oviedo played for the Double-A Wranglers, Triple-A Omaha Royals, and at the major league level. He only played in seven major league games in 2006, with a 4.73 ERA. In 2007, he was converted back into a starting pitcher. On June 22, 2007, Oviedo would have been traded to the Oakland Athletics for outfielderMilton Bradley. However, according to the Royals report, Bradley was injured at the time, and the trade was voided.
Florida/Miami Marlins
After the 2008 season, Oviedo was traded by the Royals to the Florida Marlins for first basemanMike Jacobs. In 2009, he became the Marlins closer after Matt Lindstrom was placed on the disabled list in late June. He finished the season with 26 saves. On April 1, 2012, MLB announced that they would suspend Oviedo for 6 weeks after he was removed from the restricted list. Oviedo had to get a visa to be removed. On May 28, Oviedo was suspended for 8 extra weeks for age and identity fraud. He would be eligible for one rehabilitation assignment in the minor leagues for a maximum of 16 days. He was eligible to play for the Marlins in the Major League on July 23. During a triple-A rehab game on July 16, Oviedo sprained his right elbow's ulnar collateral ligament and was later placed on disabled list. On September 6, 2012, Oviedo underwent Tommy John surgery.
Tampa Bay Rays
On January 22, 2013, Oviedo signed a minor league deal for the Tampa Bay Rays. He had his contract selected on March 31, 2013. Oviedo began the 2013 season on the 60-day disabled list still recovering from the Tommy John surgery he previously had. After missing all of the 2013 season, Oviedo had his $2 million club option for 2014 declined, and was instead paid a $30,000 buyout, making him a free agent. The Rays later re-signed him for the 2014 season. He was designated for assignment on July 26, 2014 and released on August 3.
On January 5, 2015, Oviedo signed a minor league contract with the Texas Rangers. He was released by the Rangers on March 28.
Name controversy
On September 22, 2011, the Florida Marlins placed Oviedo on the restricted list without listing a reason. The Associated Press reported that his real name was Juan Carlos Oviedo, that he was a year older than listed, and that he returned to the Dominican Republic to deal with the issue. Dominican Central Electoral Commission President Roberto Rosario said that Oviedo signed a sworn statement saying he used fake identification documents.
