The Cowboys will work McCown in slowly. Jason Garrett said McCown, who agreed to a one-year deal with Dallas on Friday, told him he has been getting ready by throwing to the quarterback's 12-year-old son.
The Cowboys nearly had a deal with McCown's brother, Josh, earlier in the offseason before the New York Jets made him an offer he could not refuse. A year ago, the Cowboys considered trading for Josh McCown when Kellen Moore suffered a season-ending ankle injury a week into training camp.
Garrett said he does not know Luke as well as Josh.
"Certainly know of him," Garrett said. "A lot of people have been around him throughout his career and I have nothing but the upmost respect for him, how he approaches it, a real professional and I'm excited to bring him on board."
Zac Dysert underwent season-ending back surgery after he suffered the injury a few days ago reaching for a bag. The Cowboys wanted to add a fourth quarterback to go with Dak Prescott, Moore and rookie Cooper Rush.
"For the most part, your objective is to sign guys that we'd like to keep," Garrett said. "We signed a receiver (Javontee Herndon) today as well. He'll be able to practice with us. We want to give him an opportunity to show what he can do. It's a hard thing for some of these guys who haven't been with us in the offseason, so they're catching up. They'll spend a lot of time with our position coaches in and around meetings, extra time at night trying to get themselves caught up and take advantage of their opportunity."