Football is the ultimate team game. There are 11 guys on the field, only two touch the ball on an average play.
The other nine are used to either block the opponent from getting to the ball carrier, or in some kind of diversionary ploy to distract the opponent.
Steelers offensive coordinator Todd Haley said earlier this year part of the reason rookie running back Chris Rainey hadn't been particularly explosive was because teams were keying on him every time he was on the field.
Rainey left the field and collapsed on the sideline in the third quarter of the Steelers' 24-20 win over the Giants in Week 9. He's saying he has a cracked rib, but he's going to play against Kansas City in Week 10.
While playing with gruesome sounding injuries like cracked ribs, or torn rotator cuffs, indicates a certain level of toughness of a player, such injuries greatly limit a player's effectiveness.
But Rainey's explosiveness can be an asset even without the ball in his hands. If he's distracting the opponents, as Haley suggested he was earlier in the year, perhaps the game plan is to have him continue participating in the same formations he has to this point in the year, but with no intention of getting him the ball.
It's not that playing with a cracked rib is impossible; anyone can block pain out and continue through it. Let's say Rainey will play Monday. Swelling that comes with it makes it much harder to breathe, which affects conditioning, quickness and focus. None of these things would help Rainey on the field, so the idea of him playing while serving as a decoy makes sense.
It's not as if the team couldn't just go with yet another trio of running backs - something they've done in nearly every game this season. Baron Batch could fill in for Rainey in sub packages, with Emmanuel Sanders returning kicks and punts (for Rainey and Antonio Brown, who's expected to miss this game). Jonathan Dwyer practiced fully Thursday, indicating he'd be ready to go, along with Isaac Redman.
Plus, holding the ball in the proper position when running would be much more difficult with a cracked rib. He could wear padding to protect it, but players often struggle to protect the ball when it's pressed to the lighter, less-dense surface area of the pad. Rainey fumbled last week simply by not protecting the ball, let alone the difficulty he'd face when gang-tackled by a group of defenders who know his rib is cracked.
But the Chiefs would still have to respect the fact he'd be out there. It would make sense to force a defender to watch him while he's out there, whether he'd get the ball or not.