De Leon was recalled by the Rays on Wednesday, Marc Topkin of the Tampa Bay Times reports.
De Leon has only appeared once for the Rays this season but has a solid 3.65 ERA in 49.1 innings for Triple-A Durham. He's offset a poor 12.5 percent walk rate with a strong 32.9 percent strikeout rate. He'll give the Rays extra bullpen depth for the stretch run. Mike Brosseau was optioned in a corresponding move.