Rainey (lower leg) was activated off the 10-day injured list Thursday, Jesse Dougherty of The Washington Post reports.
Rainey wound up missing a month with a stress reaction in his right tibia. He could be in the mix for saves down the stretch, as the Nationals dealt Brad Hand to the Blue Jays on Thursday. His 42.7 percent strikeout rate and 2.66 ERA last year would make him seem like a strong candidate, though his strikeout rate has fallen to 26.5 percent this season while his ERA has ballooned to 6.93.