McCarthy, 28, has missed time with the same injury on three separate occasions this season, and the most recent instance could potentially call for a second stint on the disabled list. Moreover, the soreness in his scapula has surfaced in four of the past five seasons, including last year, when he was out for six weeks.
"Pretty similar to what we've seen in the past, so we sent him home for an MRI and so forth, and we'll see how that goes," A's manager Bob Melvin said. "It's always kind of the same thing. He knows himself pretty well when it's sore and was experiencing that the last couple of days. We try to be proactive here and try to keep him healthy."
Because of Monday's off-day, the A's are able to push up Tommy Milone and Jarrod Parker in the rotation, with the southpaw going Wednesday and the right-hander Thursday in Denver.
In 11 starts this season, McCarthy is 5-3 with a 2.79 ERA. His place in the rotation, whether on a temporary or permanent basis, is likely to be filled by either Graham Godfrey or Tyson Ross, with Brad Peacock also an option.
- 142 wins
- 110 wins
Godfrey has been dominant at Triple-A Sacramento, going 5-0 with a 1.05 ERA in eight starts with the River Cats, compared to 0-4, 6.43 ERA in five games -- four of them starts -- with the A's.
Ross has fared well at Sacramento since being demoted by Oakland, posting a 2.45 ERA with 11 strikeouts next to five walks in 22 innings over four starts.