Rodriguez had missed the previous three games before he was back in the starting lineup on Friday. On his first-pitch groundout, though, Rodriguez aggravated his strained left calf muscle -- enough to land him on the DL after Saturday's game. He won't be eligible to return until Sept. 5.
"It wasn't like we did this on a whim. We consulted, we had him work out, we had him do things," Girardi said on Sunday. "The one thing that's always hard to simulate without sending a guy on rehab is playing in the game."
Rodriguez had said earlier in the week that he was having a difficult time gauging what he could play through since this was his first experience with a calf injury.
"I think Alex felt he was ready, too," Girardi said. "No one knows Alex's body better than he does. No one knows how he feels better than he does. You have to listen to the patient, as well, and he felt he was ready to go. It just didn't work out."
Girardi said that no tests on Rodriguez's calf were scheduled as of right now. The plan is for Rodriguez to travel with the team on its next road trip to Toronto and Chicago, where he'll be evaluated on a daily basis.
Without Rodriguez, Girardi said he plans to platoon Ramiro Pena and Eduardo Nunez at third, most likely with Pena receiving starts against righties and Nunez versus lefties. Nunez was in the starting lineup for the second straight game on Sunday against left-hander Luke French.
It isn't as if not having Rodriguez in the lineup has cost the Yankees so far this season. Rodriguez has not played in 11 games this season; New York has won all 11. Still, even if the Yankees run off 12 more wins before Rodriguez returns to the roster, Girardi will happily slot his name back in the lineup.
"Let's hope we get to that point, and then I'll put him in the next day," Girardi said with a smile. "Basically, people have stepped up in his absence."