"In the course of dealing with this calf injury, it appears that now we've got an ankle issue," Ballard told reporters, per the team's website.
"There's no question that he had a calf (strain), that he has a calf, but the lower part is more of an ankle issue. Once we get that under control, we think we can help with the pain."
Luck has been held out of practice intermittently since the spring with what had been labeled a calf strain. But on Monday evening, Colts owner Jim Irsay told SiriusXM NFL Radio that Luck was actually dealing with a "bone" injury, specifically a broken Os Trigonum, similar to an injury suffered by former Colts offensive lineman Ryan Diem in 2007. Ballard said Tuesday night the Colts confirmed that Luck was not dealing with that specific issue.
The Colts GM said Luck's new injury is at the front of his ankle and that the QB will not need to undergo surgery. Luck will instead continue his rehab.
Regarding a timetable, Ballard was not so certain as to whether the quarterback will be ready to play Week 1. Luck did not play in Indy's preseason opener and will "most likely" not play in any of the Colts' remaining preseason games, according to Ballard.
Ballard preached caution about the injury, telling reporters that this situation was unlike that from 2017, when Luck was eventually shut down for the season due to a shoulder injury.
Just last Monday, Luck told NBC Sports' Peter King he believed he will be ready to play Week 1, saying, "That's certainly the goal." Whether that's still an achievable goal is unclear.
Ballard and his Colts, however, won't be daunted by the possibility of starting the 2019 season without their franchise quarterback.
"When I first came in the door, one of the things we talked about was building a team and it wasn't going to be just about one guy," Ballard said. "Look, I understand the importance of Andrew Luck. Are you kidding me? This guy's one of the top five quarterbacks in the league. But we also got another quarterback we like in Jacoby Brissett.
"To me, that's part of building a team. You've got to be able to handle when things don't got the way you plan them out to be."