The Chicago Cubs and Oakland Athletics completed a trade yesterday, with Major League reliever Mike Wuertz headed to Oakland to help solidify the bullpen. The Cubs received back to minor league prospects: shortstop Justin Sellers and outfielder Richie Robnett.

Sellers is the better prospect of the two players. The 23-year-old middle infielder will help to fill the void left by the trade of middle infielder Ronny Cedeno, who is now a Seattle Mariner. Sellers’ batting average has taken a bit of a roller coaster ride in the past three years, while playing at A-ball, High-A, and Double-A. It has gone from .241 to .274 to .255. His line at Double-A in 2008 was .255/.333/.367 with an ISO of .112 in 439 at-bats. His rates included a 9.7 BB% and a 17.5 K%. Sellers also has the ability to steal 10-15 bases a season. Defensively, he has all the actions needed to be a successful shortstop and possesses good range. His arm, though, is average and could lead to him moving to second base on a full-time basis down the road. Right now, Sellers is a defensive-minded middle infielder who needs to get stronger and looks like a future utility player.

Robnett, a former No.1 draft pick out of Fresno State, will likely head to Triple-A to provide depth for the Cubs. With more than 10 outfielders on the club’s 40-man roster, Oakland could afford to part with the 25-year-old, left-handed hitter. Injuries took their toll on Robnett’s 2008 season and he appeared in just 82 games, split mostly between Double-A and Triple-A. In 208 at-bats at the senior level, Robnett hit .236/.307/.351 with an ISO of .115. His rates included a 9.2 BB% and a 29.3 K%. In 2007, at Double-A, he hit .267/.316/.465 with an ISO of .198. Although he’s shown some power (including massive raw power), Robnett failed to get on base at a regular rate in the upper minors, which certainly made him expendable in Oakland.

It’s a good trade for both clubs because Oakland gets a proven reliever with MLB experience and Chicago gets some much-needed depth.