I don't buy this, nothing to play for stuff though.
It's been the Colts' pattern all year to beat the shit out of bad teams and bend over for the good ones.
Where playing for something matters is how badly you fight back. Playing your game as an NFL pro is easy, but when you get punched in the mouth your character gets tested and the Colts had less in their hearts to fight back with.
Less hope without TY and less reason to play having clinched the division. When Luck threw that pick to Wilcox, the game was over. Every last gasp was squeezed out of the Colts.
A lot of it had to do with their character, but some of it also had to do with TY's absence and playing for nothing.