I've actually heard it from more than one minor league player who said they weren't heartbroken to see their teammate fail sometimes because it made their own chances at getting called up better.
Me? Personally, and to be honest, it's depend on the kid. Sometimes my son's competition has been one of his best friends on the team. In those cases, I never want to see anyone do poorly.
But, if I happened to know the player was a bad guy and/or bad teammate, then I am not feeling sad if they don't have a great game. If they have a great game, I'm cheering for them and the team. But, it's not bothering me if they don't do well.