Student or Learner
In general you have to give players you might not rate a chance.
Does It means that you have to take players you might not risk on?
You have to take players you might not give them chance?
not a teacher
In general you have to give players you might not rate, a chance.
The comma might help.
This is "rate" in the sense of "consider worthy", "have high regard for".
e.g. "I don't rate this player, he doesn't have good skills."
So he is saying that even if he doesn't regard the player very highly, he would still give him a chance to prove himself.