Good addition Wolf, certainly different but directly related. I think both are prevalent and both can be addressed. The first step is identifying the cause.
Often the previous issue is caused by a lack of proper motivational mechanisms in either the program or the kid.
The issue you bring up can be caused by a multitude of factors, one of the primary causes is mental toughness.
I've also seen kids that just "over hype" themselves for games and baseball is not well suited for that.
I won't say much on this since it isn't directly on topic, but the one thing I would say to coaches is that if you're experiencing this a lot, you may indeed be a major cause yourself. A lot of coaches are relaxed and instructional in practice and then nervous and reactionary in games.
Never underestimate your own impact on the mentality of the team, or individuals on it.