When will J.J. McCarthy start for Giants? Why John Harbaugh could make QB change sooner than expected

McCarthy must learn a new offense and prove he can protect the football, but Jameis Winston's uneven play could speed things up

Sep 29, 2026 at 7:41 am ET • 3 min read

John Harbaugh didn't come to New York to lose. The 64-year-old Super Bowl-winning coach plans to win early and often with the Giants, who are 2-1 and an early-season NFL surprise. 

Harbaugh's expectations do not change despite Jaxson Dart's season-ending injury (the Giants also lost Brian Burns to a season-ending injury on Sunday). He admitted Monday that as soon as Dart went down, he and the Giants' brass sought to improve their quarterback room. That led to Monday's trade for JJ McCarthy, a former first-round pick whose time with the Vikings was as odd as it was bizarre. 

Injuries, inconsistent play and the arrival of Kyler Murray (and McCarthy's response to it) prevented McCarthy from realizing his potential with the Vikings, who are off to a 3-0 start this season. When McCarthy was on, he showed flashes of the player that compelled Minnesota to take him with the 10th overall pick in the 2024 draft. 

"I think he's a strong, young quarterback, has some experience in the National Football League," Harbaugh said of McCarthy, who just three years ago led Michigan to a national title under for Jim Harbaugh. "Obviously, was a very high draft pick, very talented player and is going to make us a stronger football team."   

John Harbaugh has had success changing quarterbacks during a season. In 2018, he replaced Joe Flacco with then-rookie Lamar Jackson after Baltimore started 4-5. Jackson went 6-1 as Baltimore's starter that season while foreshadowing what was to come for the eventual two-time league MVP. 

No one is comparing McCarthy to Jackson, but it's certainly possible that McCarthy -- if nothing else -- can provide temporary stability for the Giants at the NFL's most important position. 

When would McCarthy replace Jameis Winston as QB1?

Week 9 would be the logical answer given the Giants' Week 8 bye. There's a very good chance, however, that McCarthy will make his debut as the Giants' starter much sooner than that. 

Let's start with the fact that the Giants' Week 9 game will be in Philadelphia, which isn't exactly a great place for a young quarterback who is making his first start with a new team. If the Giants do decide to wait until after the bye to start McCarthy, their Week 10 home game against the Commanders would make more sense. 

In Harbaugh's perfect world, Jameis Winston would play well enough to keep the job. Changing quarterbacks in-season is a tall order, especially for a first-year coaching staff. 

Winston's recent performances, however, would suggest that Harbaugh will likely need to make a quarterback switch soon. Winston struggled mightily against the Rams. He was much more accurate on Sunday against the Titans but he only managed to throw for 118 yards while averaging just 8.4 yards per completion. 

If today's Giants were built like the 1990 Giants (who won a Super Bowl with a backup quarterback), there's a chance that they could stay in the hunt with Winston. The Giants don't have an offense that can carry a quarterback; while their defense is good, Burns' injury reinforces that New York can't rely on it to carry them on a weekly basis. 

If Winston doesn't improve over the next two weeks, it's certainly possible to make a change when New York hosts the Saints in Week 6. That would give him time to watch Winston against the Cardinals and the Commanders (in Washington) before taking the reins. It would also give him two games of work heading into the bye week. 

Along with learning the offense, McCarthy will have to prove to Harbaugh that he can take care of the ball. That was a huge issue in Minnesota and was likely one of the reasons why things didn't work out with the Vikings. That will have to change. McCarthy is going to make the most of his second chance, whenever that happens.