4. C Frank Ragnow
Ragnow gutted through a recurrence of the toe issue that cost him a big chunk of the 2021 season last year, all the way to being the only Lion voted in to the Pro Bowl. He'll be playing with the issue to some degree until further notice by the sound of it, perhaps the rest of his career.
Evan Brown filled in very capably for Ragnow in 2021, but he left for the Seattle Seahawks in free agency this offseason. Former Lion Graham Glasgow was brought back in a subsequent move, and if Halapoulivaati Vaitai takes back the starting job at right guard he would be Ragnow's backup at center. But it's also safe to say Glasgow has had a rough last couple seasons, due in part to injury.
Ragnow seems to walking a fine line betwen being able to play with his injury, and possibly facing significant missed time like in 2021. The difference could literally be an awkward step or someone stepping on his foot. Losing the literal center of one of the league's best offensive lines would not be good for the Lions.
3. WR Amon-Ra St. Brown
St. Brown has been one of the most productive receivers in the NFL over the last two seasons, and he's eyeing being a bigger threat all over the field in his third season.
St. Brown is no-doubt going to be the Lions' No. 1 wide receiver, but target share and overall impact. But the group around him got a little thinner for the early part of the season, when Jameson Williams receive a six-game gambling suspension. So St. Brown's performance will now have a little bit more spotlight on in over those six games, and more importance to the functioning of the Lions' passing game.