Try and get him to learn something every game, ask him, what he's learnt?
Try and get him to look at as many aspects of the game as possible, ie fielding changes,did they work?
If he just focuses on one thing,say his batting, and he either doesn't get a bat or has a bad knock, ,it's easy to get down about the whole day. But if he's looking at the whole game, whatever happens, he should be able to take away something positive.
A huge thing for me, and one thing I've told my son to always work on, ,is fielding
I remember my son and his cousin,playing for our midweek team years ago,they were both about 10, ,we never lost a match while they played! They were only making numbers up, but their fielding was enough to make the difference between winning and losing.
Tell him to chase everything, get something in the way of the ball,throw straight, , ,etc
And remember, there's a fine line between encouragement and being pushy.