Mack (concussion) didn't practice Wednesday, putting his availability for Sunday's game in Jacksonville in serious question, Kevin Bowen of 1070 The Fan Indianapolis reports.
The nature of the NFL's concussion protocol makes it difficult for a player to gain clearance by Sunday without logging some level of participation early in the week. Mack thus needs to practice in at least a limited capacity Thursday or Friday to have any realistic shot at avoiding a Week 13 absence. The Colts likely are preparing for Sunday's game under the assumption Nyheim Hines and Jordan Wilkins will handle most of the backfield work.