6. LB Alex Anzalone
Anzalone is moving over to WILL linebacker this year, but he is surely going to still be wearing the "green dot" to communicate defensive calls on the field. Getting everyone where they need to be, in a loud environment with hand signals to do so as he plays a chess game with Mahomes, will be more critical than anything tangible he does statistically on Thursday night.
That said, Anzalone may be a key part of the Lions' plan to defend Kelce, assuming the Chiefs' top pass catcher suits up. He has allowed less than an 80 passer rating in his coverage each of the last two seasons (per Pro Football Reference), which honestly defies what the eye test says at times.
Anzalone has to be at his sharpest mentally against the Chiefs, even moreso than not making any physical mistakes.
5. LB Jack Campbell
Derrick Barnes is in line to start alongside Anzalone on Thursday night, the rookie Campbell will surely see some significant snaps in his NFL debut and he is the most rawly all-around talented linebacker the Lions have.
Woodward Sports pointed to Campbell as someone who needs to perform well against the Chiefs, as a run defender, in coverage or even as someone to get after Mahomes at little.
Even if it's only for something like 20-25 snaps in the game, Campbell can be very impactful against the Chiefs' offense regardless of who is available. At minimum, he needs to not make any glaring mistakes in the big spotlight of his NFL debut.