Without dissing Cam, I'm pretty sure be wants to start and to come out only when he physically needs a rest for a play or 2. Similar to Gurley/Brown of the past. But because Kyren has shown more in pass blocking, receiving and even running Cam is being slowly overtaken. I'm sure Cam wants a chance to prove himself to be the main guy this year, but apparently McVay doesn't see it that way and thinks Kyren has earned more touches.
In game 1, Cam had some nice runs but later was getting drilled in the backfield for losses. Whether his fault or not, the defenses read run when he was back there and played it that way. Maybe not tells, just tendencies and %s.