"It has been a tough last few days for me as I keep replaying in my head when the ball struck Brandon," Aybar said in a statement. "I am encouraged and thankful to know that he is making significant progress and keep praying to God to please help him recover quickly and fully.
"Our game is a tight brotherhood and right now we all wear the same uniform colors."
Aybar's hit came with two outs in the fourth inning of an eventual 7-1 win for the Halos at Oakland Coliseum.
McCarthy had surgery for a skull fracture and brain contusion on Wednesday and was in stable condition in the critical care unit at a Bay Area hospital on Thursday.
"From the moment Brandon was struck by that line drive, he has remained in our thoughts and prayers," Angels general manager Jerry Dipoto said in a statement. "That support will continue for Brandon and his wife Amanda as he begins the recovery process from yesterday's surgery.