Crosby made just 3 of 8 field goals, including going 2 for 6 in a kicking competition at the end of the scrimmage in front of 63,047 fans, many booing the kicker.
"He's definitely got to do better than that, because that's not going to cut it," McCarthy said, per the Green Bay Press Gazette.
Crosby missed from 33, 37, 43, 48 and 53 yards, while making 40-, 47- and 51-yarders.
The seventh-year Packer said he was disappointed but wasn't worried about losing his job.
"No, I've been hitting the ball well," Crosby said. "Obviously extremely disappointed with how I hit it tonight. Have to evaluate that and break it down. I can't think about things like that. I just have to go and actually work on things, make sure I hit the ball through the uprights. That's all I can really worry about and focus on right now."
Crosby's competition, Giorgio Tavecchio, the former California Bear, went 6-for-7 Saturday. Tavecchio is now 16 of 19 during training camp, according to the Press Gazette, while Crosby's terrible night dropped him to 12 of 19.