Fleming was optioned to Triple-A Durham on Sunday, Marc Topkin of the Tampa Bay Times reports.
The 24-year-old made his major-league debut last season and impressed with a 2.78 ERA, 1.08 WHIP and 25:7 K:BB over 32.1 innings, but he won't begin 2021 in the big leagues. The move isn't performance related, as Fleming gave up only three hits with an 8:1 K:BB over 8.2 innings during spring training. The young southpaw should receive a starting opportunity for the Rays this season, but he'll open the campaign in the minors.