Colvin, 26, has hit .215 in 221 games while spending parts of 2009 and 2011 and all of 2010 with the Cubs. In 2010, he hit .254 with 20 home runs, 18 doubles, five triples and 56 RBIs. LeMahieu, 23, a second-round Draft pick in 2009, made a 37-game Major League debut in 2011 and hit .254 with two doubles and four RBIs in 37 games. LeMahieu, who plays second base and third base, has hit .317 in 284 career Minor League games.
"Both players will be given an opportunity to compete for spots on our 25-man roster," Rockies general manager Dan O'Dowd said.
Stewart turns 27 on April 5, with hopes the new year and new team brings new results. Bouncing between the Rockies and Triple-A Colorado Springs, playing through a hamstring injury early and missing time with a wrist issue late, Stewart hit just .156 with no home runs and six RBIs in 48 Major League games last season.
"We have seen him grow as a person and a player and wish him nothing but the best in this start," O'Dowd said.
Weathers, 26, was making fast progress before suffering a right elbow injury during Arizona Fall League play in 2008 and undergoing Tommy John surgery. Last year at Double-A Tulsa, Weathers demonstrated he had regained upper 90s velocity, but was still searching for command.
The trade is part of an active period for the Rockies, who have dealt utility man Ty Wigginton (to the Phillies for a player to be named), catcher Chris Iannetta (to the Angels for second-year pitcher Tyler Chatwood), former closer Huston Street (to the Padres for a player to be named) and now Stewart. Iannetta and Stewart were selected and developed by the Rockies, who are showing a new willingness to deal such players. The aim is to acquire talent, open opportunities for talented prospects or make it easier to make other moves.
Colvin and LeMahieu in exchange for Stewart increases payroll flexibility. Stewart could make as much as $2.6 million via arbitration. Colvin is not eligible for arbitration until 2014, and LeMahieu has just 37 games in the Majors. The Rockies also escaped half of a $4 million commitment to Wigginton and $7 million of Street's $8 million salary for 2012.
The Rockies also added right-hander Kevin Slowey from the Twins for a player to be named, at a projected $2.7 million through arbitration. The catching change is for a slight dollar savings on 2012. To replace Iannetta, who was guaranteed $3.8 million in 2012, the Rockies signed veteran catcher Ramon Hernandez to a two-year, $6.4 million contract that gives him $3.2 million in 2012.
The Rockies continue to seek an innings-eating starter and remain players in the trade market and free agency, specifically for righty Hiroki Kuroda. The Rockies also have the opportunity to commit payroll to a pursuit of free-agent outfielder Michael Cuddyer, who has an offer from the Twins -- the only team for which he has played.
Another possible free-agent target is outfielder Cody Ross, who could be a right-handed platoon partner with left-handed-hitting Seth Smith. Several teams have approached the Rockies about Smith, but no deal has been found so far. The Rockies see no problem with holding onto Smith, a career .290 hitter against right-handed pitching.