Koshansky was selected by the Colorado Rockies in the 6th round (170th overall) in the 2004 Major League Baseball Draft.

His performance earned him Baseball America's Rockies Minor League Player of the Year Award.

He was selected as the Rockies Minor League Player of the Year again when he hit .284 with 31 home runs in 132 games for Tulsa.

His strong performance earned him a callup to the Colorado Rockies on September 1 when rosters expanded.

He made his major league debut on that same day against the Arizona Diamondbacks as a pinch hitter in the ninth inning against Brandon Lyon.

[2] On September 17, 2008, Koshansky hit another home run off Josh Geer in a 1-0 win over the San Diego Padres.

[4] On April 30, 2011, in a game against the Bowie Baysox that lasted 18 innings, Koshansky went 0 for 8 with 7 strikeouts, tying a Minor League Baseball record.