The Cubs selected Wesneski's contract from Triple-A Iowa on Monday.
In a corresponding move, Chicago moved starter Justin Steele (back) to the 15-day injured list. Wesneski looks to be the top candidate to assume Steele's spot in the rotation this weekend against the Giants, assuming the 24-year-old righty isn't needed Tuesday against the Reds to serve as a piggyback pitcher behind starter Wade Miley (shoulder), who may be on a limited pitch count in his return from the 60-day IL. Acquired from the Yankees in the Aug. 1 deal that sent reliever Scott Effross to New York, Wesneski generated a 3.92 ERA and 1.16 WHIP while striking out 106 across 110.1 innings between Iowa and the Yankees' Triple-A affiliate in Scranton/Wilkes-Barre.