The Diamondbacks placed Sewald on the 15-day injured list Sunday with left neck discomfort.
The timing of Sewald's move to the IL means that he won't be eligible to return until the Diamondbacks' final series of the regular season, which begins Sept. 27. Even before the neck issue cropped up, Sewald's fantasy value had been on the downturn with Justin Martinez having started to build up security as the Diamondbacks' preferred closing option. Sewald didn't help his case for regaining the closer's gig after giving up at least one run in four of his last six appearances before landing on the IL.