Steele was optioned to the Cubs' alternate training site Saturday, Tony Andracki of Marquee Sports Network reports.
Steele joined the major-league bullpen Monday after three pitchers were placed on the COVID-19 injured list. The southpaw allowed two hits and one walk while striking out four in 3.1 innings across three relief appearances in the big leagues. He'll return to the team's alternate site after Brandon Workman and Dan Winkler were reinstated from the COVID-19 IL on Saturday, but Steele could be a candidate to serve as bullpen depth later in the season.