He played in Major League Baseball (MLB) for the Oakland Athletics (1993–94, 1997, 2006), Cleveland Indians (1998–2001), Atlanta Braves (2001), New York Yankees (2002, 2004–05), and Texas Rangers (2005).

[1] Karsay was a "star pitcher" at Christ the King Regional High School in Middle Village, Queens.

[3] A 1st round draft pick of the Toronto Blue Jays in 1990, Karsay was traded to the Athletics along with outfielder José Herrera for Rickey Henderson on July 31, 1993.

A starter in his early days with the Athletics, Karsay worked mostly in middle relief and as a set-up man from 1998 on, although he also had some notable success as a closer in 2000 with the Indians and 2002 with the Yankees.

[5][6] Finally, at age 34, Karsay announced his retirement on June 18, 2006, the day after pitching two scoreless innings against the Los Angeles Dodgers and getting the win in a 17-inning marathon for the Athletics.