But even that's not a guarantee. McCarthy will have to exit his bullpen session Thursday without "anything that gives me caution or pause," he said, in order to be cleared for the outing against Detroit. However, he already underwent an MRI that came back clean.
McCarthy insists the soreness in his right shoulder isn't serious, particularly compared to what he's experienced in the past and, most recently, last year, when he missed six weeks because of a stress reaction in his right scapula. The same injury has surfaced in four of his past five seasons, and McCarthy believes he's taking extra precautionary steps this time.
"I'm trying to find it earlier and earlier," he said. "The way some people can tell it's going to rain, I guess I could kind of see this coming, so I was trying to stay out in front of it. A few days off is probably the best way to go about it.
"This becomes unchartered territory, because I've never been this far in front of it. Usually I've kind of run up to the wall, and last year I shut it down earlier than I had in past years. This year, I'm trying to deal with it before it's even an issue. Finding the right way to get around it hasn't been figured out yet, but hopefully we're doing that."
The injury-prone McCarthy, who has endured six career disabled list stints, first noticed something was off the day after his 113-pitch outing in Boston, where he gave up just one run in 6 2/3 innings. Over his last three starts, he's 2-1 with a 2.18 ERA.
He came out of his Sunday bullpen session feeling fine and is scheduled to play catch on Wednesday, before throwing long toss and undergoing another bullpen Thursday. He admitted a DL stint would be likely if he's unable to go Saturday, particularly since the A's would need a spot starter and could backdate the transaction to May 2, but he didn't seem at all interested in deeming such a scenario probable.
"When I say it's not even on the same universe [as last year's injury], it really isn't," he said. "Last year it was mandatory. I could barely breathe without wincing. This is nothing. It's a step above a premonition that something doesn't feel quite right."
Jarrod Parker, initially scheduled to pitch Wednesday, started Tuesday's game against the Blue Jays, with Tyson Ross now set to go Wednesday and Bartolo Colon and Tommy Milone to follow.