1. QB Jared Goff
Goff had a very good season in 2022, literally one of the best of his career. His ability to repeat it, or at least somewhat closely repeat it (no one should expect 300-plus more pass attempts without an interception) will be a barometer of success for the Lions this season.
At the practical outset of the offseason, Lions general manager Brad Holmes declared priority on the No. 2 quarterback spot. That ultimately yielded bringing back Nate Sudfeld, and reports in April about a "strong offer" to Teddy Bridgewater. Bridgewater not taking said "strong offer" is not the Lions' fault, but he can't have been the only plan to upgrade the backup situation behind Goff. Or he shouldn't have been, anyway. Now, everyone is saying how comfortable they are with the quarterback room.
Independent of broader thoughts about Goff's upside or his ability to repeat his performance from last year, which for some fans you shouldn't talk negatively about, the Lions will have a hard time winning any games he misses and Sudfeld has to start this season. Maybe not quite Tim Boyle circa 2021, but closer to that than anyone would like.
The high hopes for the Lions in 2023 go down with Goff if he is sidelined by a serious injury. After Holmes practically promised that wouldn't happen back in January, the failure to really address the backup situation only heightens how important Goff is (performance and health-wise) to the team's success this season.