Koskie was drafted by the
Minnesota Twins in the 26th round of the
1994 Major League Baseball draft, and subsequently made his MLB debut on September 9, 1998. He established himself in 1999 as the Twins'
third baseman of the future by
hitting .310 and
knocking in 58 runs. In 2000, he batted .300 with a .400
on-base percentage and in 2001 had his most productive offensive season when he hit 26
home runs, had 103 RBI, and scored 100
runs. Koskie signed a three-year, $17-million contract with the
Toronto Blue Jays on December 14, 2004. An injury-plagued season cut his productivity and playing time, as he struggled with a .249 average, with 11 home runs, 36 RBI, and 4
stolen bases in 97 games. Despite his frequent injuries, Koskie was regarded as one of the more athletic third basemen in the game. On January 6, 2006, he was traded by the Blue Jays to the
Milwaukee Brewers for pitcher
Brian Wolfe. The deal was widely viewed as a salary dump for the Blue Jays after the team traded for
Troy Glaus. With several players on the roster capable of playing third base (Koskie, Glaus,
Eric Hinske,
Shea Hillenbrand, and
Aaron Hill) and no assurances of regular playing time from Blue Jays
general manager J.P. Ricciardi, Koskie was traded just a year after being the Blue Jays' 2004 offseason marquee
free agent signing. While the Brewers acquired a veteran infielder with a solid glove and bat to anchor their very young infield, Koskie's later seasons were marred by injuries, including missing most of the
2006 season with
post-concussion syndrome from an injury he received on July 5, 2006. "If I can't play, I at least want my life back", he said. "I'm hoping to do something to help the team this year. I want to play baseball again. If I can play baseball, I know I'm fine." The injury caused him to miss the entire 2007 season. In , Koskie worked out at the Minnesota Twins spring training camp and played for
Team Canada in the
World Baseball Classic. On February 28, Koskie signed a minor league deal with an invitation to spring training with the
Chicago Cubs. On March 21, 2009, Koskie announced his retirement. While confident in his abilities, he did not want to risk his health. His fear of injury led to a diagnosis of
post traumatic stress disorder. ==Post-retirement==