Calvin Johnson may have been playing with a partially torn PCL, according to Deadspin.
Granted, plenty of players have played with a similar injury. However, if he has been injured for that long, he's put in more than two months of wear and tear on a damaged knee.
His presence was vital when the Lions were chasing the NFC North title. With the playoffs no longer an option, resting "Megatron" to prevent further damage would be prudent.
If Johnson doesn't play, Matthew Stafford won't have a deep threat and will be forced to check down to his running backs more often.
And that's not a bad thing. Joique Bell and Reggie Bush are both capable receivers (Bell caught all 10 of his targets last week) and will be facing off against a linebacking corps that doesn't elicit too much fear.
Chad Greenway and Erin Henderson have combined for 29 missed tackles this season. Bell forced five alone last week, and Bush's elusiveness is his greatest asset.
What does this all mean? That the running backs should find plenty of opportunities to shrug off would-be tacklers and rumble for yards after the catch.