Originally signed by the Tampa Bay Devil Rays as a free agent in 1996, DeCaster was selected by the Pittsburgh Pirates from Tampa Bay in the 2000 minor league phase of the Rule 5 draft. DeCaster was one of just three players to hit three home runs in the 2004 Summer Olympic Games in Athens, Greece, while playing for the Netherlands team. He spent the entire 2005 season with Triple-AIndianapolis Indians, where he made 28 appearances at third base, 25 at first base, 13 at second base and 58 in the outfield. He posted a.280 batting average with 11 home runs and 61 RBI, and also led his club in games played and doubles. Besides, he had a productive 2005–2006 season while playing for the Caribes de Anzoátegui of the Venezuelan Winter League, when he batted.325 with 17 home runs and 47 RBI in just 60 games. His 17 home runs tied him with Tom Evans for the league lead. In 2006, DeCaster returned to Indianapolis, with whom he spent most of the season. In 119 games with the Indians, he batted.273 with 11 home runs and 51 RBI. He was called up to the Pirates twice, from May 21–24 and June 5–13, and appeared in three games. He struck out in both of his at-bats in the majors. He was released on December 9, 2006, but came back to Pittsburgh in 2007 and spent the whole season in the minor leagues with them. On November 27, 2007, DeCaster signed a minor league contract with the Washington Nationals that included an invitation to the 2008 spring training. He then was assigned to the Double-A Harrisburg Senators of the Eastern League to begin the regular season, becoming a free agent at the end of the season. In February 2009, DeCaster signed a minor league contract with the Detroit Tigers, but was released in April. He began the 2009 season with the Fargo-Moorhead RedHawks of the Northern League, but on June 29, 2009, DeCaster's contract was purchased by the New York Yankees, who assigned him to the Triple-A Scranton/Wilkes-Barre Yankees. He was released on September 2. He later played with the Reynosa Broncos of the Mexican League in 2010 and 2011, collecting a.339 average in 101 games for them in his season debut. He entered 2012 with the Olmecas de Tabasco, before joining the independent Winnipeg Goldeyes of the American Association during the midseason. He won the league championship, as the Goldeyes swept the Fargo-Moorhead RedHawks in the first round, 3 games to 0, and did the same with the Wichita Wingnuts in the championship finals 3 games to 0. DeCaster played with the Goldeyes for the 2013 season as well.