Quality of competition on the entire roster will determine whether the Packers keep three quarterbacks on their opening-day roster for the first time since 2008.
The Packers return Matt Flynn and Scott Tolzien, but haven't started the season with three quarterbacks since Flynn's rookie year when he and second-round pick Brian Brohm spelled Aaron Rodgers.
"I'm not opposed," McCarthy said. "Ted's not opposed to keeping three quarterbacks. It really depends on the competition at the other positions."
With Bryan Bulaga and Derek Sherrod back to full health, the Packers feel their offensive line room is the deepest it's been during McCarthy's nine years as head coach.
The Packers return four of their five preferred starters with 2013 fourth-round pick JC Tretter the leading candidate to replace Evan Dietrich-Smith at center.
They should have all 15 of their offensive linemen available for today's first training camp practice with several veterans vying for snaps behind second-year left tackle David Bakhtiari, guards Josh Sitton and T.J. Lang, and Bulaga, who returns from a torn anterior cruciate ligament.
"I love our experience level," McCarthy said. "I think our core with the two guards. JC, this will be his first time and (Corey) Linsley, I was very impressed with him in the spring. ... The core and our mode of operation in line with their ability and their production, I think has a chance to be really good."
McCarthy wants to start the season faster, but won't sacrifice player evaluation in the final two preseason games to do so.
"That Kansas City game's a critical game for our younger players," McCarthy said. "I mean, I can't tell you how many times you go into the last game of the year and it changes."