Reeves was signed last February and, really, he was an afterthought until Brandon Flowers was injured in training camp. When Flowers was out in Week 1, it was Reeves who played every defensive snap in place of him. The next week he didn't play one defensive snap. And now he's done.
A good example of the fluid nature of the NFL.
This does affect the Chiefs depth at cornerback. Right now, Flowers, Stanford Routt and others are healthy so the front line is fine. Reeves was listed third on the depth chart behind Flowers and Jalil Brown.