The Rockies, as you may know, have had absolutely miserable production from the 3B position. Starter Ian Stewart lost the job after an absolutely miserable (and ill advised) April. Ty Wigginton has done an alright job filling in for Stewart, but his lack of defensive prowess has sunk the value in his league-average bat at the hot corner. Former 1st round pick Chris Nelson has been flashing the glove somewhat at 3B, but his bat leaves a lot to be desired as well.
Kouzmanoff, 30, isn't exactly having a top-notch season either. Batting a mere .221/.262/.353 on the season, the former Evergreen High School student might be looking for a change of scenery boost - getting out of Oakland should help, anyhow.
Bottom line is that acquiring Kouzmanoff really speaks to how poor the 3B situation has been for Colorado this season.