Why they won't be: Injury bug
Injuries in the NFL are something that teams can never prepare for, but generally, always happen. It's unfortunate, but they seem to always happen to every single team.
In some years, it seems like the injury bug tends to hit the Giants harder than most teams, especially when they have had seasons where they have anywhere from 20-30 players on the injury list or Injured Reserve. Barkley's ACL tear in 2020 put a damper on their season when it took him out for the final 14 games, as did Jones' neck injury for the final six games back in 2021. Fortunately for the Giants, both players were healthy and were keys to the 2022 team that made the playoffs.
The Giants will need both of them healthy again, as they will for several of their key players on both sides of the ball. Players like Dexter Lawrence, Kayvon Thibodeaux, Adoree' Jackson, Xavier McKinney and Leonard Williams all experienced injuries at some point during the 2022 season and for various amounts of games. Having them healthy on defense would help the Giants chances of winning.
However, if any were to miss significant time, it can hurt the Giants chances of stopping teams from putting points on the board. It goes for the other side of the ball, as the Giants will need Jones, Barkley, Waller and Andrew Thomas to remain healthy and on the field.
If the Giants can avoid injuries, it'll help their chances. But again, there is no preparing for them when they happen, so the toughest opponent the Giants could face would be the injury bug.