Jeffrey ("River Wizard") Wayne Karstens (born September 24, 1982, in San Diego, California) is a right-handed starting pitcher for the Pittsburgh Pirates.
Karstens attended Mount Miguel High School in Spring Valley, California. In his senior season, he was the team's Most Valuable Player, a First-Team All-Conference Honors selection, and a Second-Team All-San Diego selection. In his senior year, he posted an 8-2 record with a 2.99 ERA. After high school, Karstens attended Grossmont College and Texas Tech University in Lubbock, Texas, where he played for the Red Raiders.
Karstens was drafted in the 19th round of the 2003 Major League Baseball Draft by the New York Yankees. He played the 2005 season with the Yankees' Double-A affiliate, the Trenton Thunder, posting a 12-11 record with a 4.15 ERA and 147 strikeouts. He led his team in wins with 12 (3rd most in the league), in Games started with 27 (2nd in the league), and in innings pitched with 169 (4th in the league).