Ballard isn't ready to say what Luck's status will be for the Week 1 game at the Chargers.
"We're 3 and a half weeks away from regular season, so I'm not ready to say (Luck's regular season is in jeopardy)," Ballard told reporters on a confereence call Tuesday night.
Ballard says "most likely" Luck will not play in the preseason.
Team owner Jim Irsay told SiriusXM NFL Radio on Monday that Luck's ongoing absence from Colts training camp was related to a bone issue in his lower left leg.
The quarterback has been ruled out of practices through Thursday, including a pair of joint sessions with the Cleveland Browns that begin Thursday, according to coach Frank Reich. He has been a participant in walk-throughs and has worked with throwing coach Tom House.