Pelfrey's back locked up Wednesday preventing him from participating in any physical activities, Matthew B. Mowery of The Oakland Press reports.

EDGE Analysis

Pelfrey was placed on the 15-day DL on Tuesday and will likely take a few days to rest before beginning his rehab. The 30-year-old has a 4.76 ERA on the season but is coming off a solid outing where he pitched shutout five innings while only giving up four hits and one walk. His status should be monitored as he progresses through his recovery, but he will not be eligible to return until August 16 at the earliest.