Holmes said Tuesday he's been dealing with back spasms for the past couple days, and he may require a stint on the injured list, Lindsey Adler of The Athletic reports.
The right-hander first had the issue crop over the weekend, and he experienced it again when throwing off a mound Tuesday. Holmes is set to rest and receive treatment, which is an indication he may require a stint on the 15-day IL. The 29-year-old's grip on the closer role was already slipping since he has surrendered seven runs and has three blown saves over his past five outings, and it now appears he'll be out for a couple weeks. Aroldis Chapman hasn't been scored upon in his past nine outings and is likely to reclaim ninth-inning duties if Holmes is out.