Rucker was returned to the Cubs by the Orioles on Friday, Roch Kubatko of MASNSports.com reports.
Rucker was the 11th pick of the Rule 5 draft in December, but the Orioles elected not to carry him on the major-league roster after a couple weeks of spring training. The 25-year-old finished 2019 at Triple-A Iowa, but he spent most of the season at Double-A Tennessee and had a 4.28 ERA, 1.30 WHIP and 89:22 K:BB over 75.2 frames.