But a amusing thing happened along the way: The 38-year-old McCown has had the best season of his 15-year career and established himself as an emotional leader who has the Jets still thinking playoffs in early December.
Hackenberg, a second-round pick in 2016 out of Penn State, will thus go two full years without seeing regular-season action.
Coach Todd Bowles has previously implied McCown would maintain his job, but he left little doubt this time around.
So McCown will be the guy the rest of the way? "That's what I've been saying". Last Sunday, McCown threw for 331 yards and a TD and also ran for two scores in leading NY to a 38-31 victory over Kansas City.
It came as no shock to McCown.
"It's always good, that was my plan and expectation to hear that", McCown said of starting the rest of the season. I just need to keep working and keep developing those things that I need to develop and be as prepared as I can when that opportunity does come. "I had every expectation of doing that anyway, so glad to hear it and I'm excited about it".
"As a competitor, you obviously want to play". "That was my mindset going into each week". For me, my mindset, and every guy in this locker room, when your number's called, you play until you're not in.
Hackenberg, who has apparently learned a lot from McCown, fully understands this decision. Hackenberg is the great unknown. "He's played at a really high level". Just how he works, how he operates, how he plays. "So I can't really control anything else".
Hackenberg is right. His mentor has earned the right to keep going, leading a team that some predicted would go 0-16 to a 5-7 mark through the first 12 games. McCown's 68 percent completion rate ranks fourth in the National Football League, and among players with more that 205 pass attempts McCown is 10th in passer rating (96.7). McCown's also run for five scores.
The veteran has made it impossible to employ what was perceived as the initial plan - to eventually get Petty and Hackenberg some reps once the season had tanked. Petty, a third-year pro, is the backup who is trying to build his resume after four underwhelming starts in 2016. "I know that for a fact", Petty said. "I guess it just confirms it".
"Patience is the key", McCown said. And when, are you ready? Taking extra time to throw whenever I can to throw, or work mechanical things. "For them, I watch them work every day and they work really hard on the practice field and in the film room, so I do believe that wholeheartedly - that when their next opportunity comes, they're going to be better for it because of the work that they put in right now".
And, McCown might be the ideal complement to whomever is drafted even if that means moving from the huddle to the sideline next season.