But the Rangers are hoping McCarthy will be the right guy at the right place Saturday, when he is expected to join the Texas rotation for the first time this season against Cleveland.
The Rangers didn't announce what roster move would be made to make room for McCarthy on the 25-man roster and don't have to make a move until the right-hander is activated Saturday.
McCarthy's return to Arlington on Tuesday came 12 days after he made a special visit to Rangers Ballpark to have team president Nolan Ryan, pitching coach Andy Hawkins and bullpen coach Jim Colborn help him with his mechanics.
Ryan, Hawkins and Colborn focused on getting McCarthy to utilize his lower body when coming to the plate and keeping balance in his windup. The visit has paid dividends for McCarthy, who's been on the disabled list all season with severe inflammation in his right forearm and was shut down twice during his rehabilitation.
In two starts since the session, McCarthy has thrown 13 straight innings of shutout ball at Triple-A Oklahoma and posted 11 strikeouts and just two walks.
With the strides he made since meeting with Ryan, Hawkins and Colborn, McCarthy had a hunch he was back on track to the big leagues.
"The last two weeks felt like it would come soon," McCarthy said. "I honestly didn't think about it and I wasn't concerned about it. If I had to stay down there the rest of the year to get straightened out, I would have stayed down there the rest of the year. Now, I'm just excited to be back here.
While McCarthy has been out of commission much longer than expected, manager Ron Washington didn't doubt that McCarthy would return at some point this season.
"To be honest, I thought he'd be back," Washington said. "I thought he'd be back by Sept. 1. For about a month now, it's just been a progression for him."
With as much uncertainty that's surrounded McCarthy this season, there's little doubt he wouldn't be back with the Rangers if he hadn't worked with Ryan, Hawkins and Colborn on Aug. 7.
Prior to the visit, McCarthy said his velocity was down to 86 mph from its usual 89-93 mph range and his command wasn't what it once was.
And, more than anything, McCarthy's confidence has returned along with his stuff since then.
"I was able to build on what I worked on here," McCarthy said. "I think it showed up in my results and it showed up in how I pitched.
"It's fun being able to go out and throw the pitches I want to be able to pitch and not have to worry about where they're going. It's fun feeling like myself again."