He's almost two years removed from an ACL. There wasn't an additional injury last year -- just a slow recovery and swelling. He could have been active for the final games of the season -- but the Chiefs, understandably, saved the roster spot for their (abbreviated) post season run. 

 I would be surprised if he's not healthy and a key contributor on week one.

He does make one good point. There are suddenly a lot of skill players and only so many snaps. How to get the two  slot rookies involved, a new scat back rookie and three RBs. Plus the WRs and TEs