Keep It Cool
The worst thing you can do is overreact. People are very reactionary, so coaches must never react spontaneously. After a big loss all coaches should have a cooling-off period.
When we bring too much emotion into the game we have a tendency to make bad decisions. So, as a coach, if you are feeling emotional after the game then take a minute and reach for that score book, study it and really analyze where the mistakes were made.
Identify and Fix Mistakes
If the mistakes were mostly physical, those can easily be corrected. For example, defensive errors, base running errors, not getting bunts down, etc. These errors you can work on in practice. It's the mental errors, the lack of hustle, that typically hurt more than physical errors.
I recommend that these be addressed in a classroom manner. You can do this by dissecting film, dissecting the book, manners of the heart, the will and the desire of the team. If there is a lack of desire to win then that is the rotten apple that can spoil the bunch. It is important to really take control of those issues before they get out of hand.
With this in mind, it is crucial that you pay attention to whether or not they were focused and their heart was in the game. If your players were invested in the game you must make sure you do not berate or discourage them. This could make them lose their confidence. An unconfident team will never be a successful team.
When disciplining an athlete you have to be very cautious how you talk to them, especially the female athletes. You get more with honey in life than you do vinegar, so make sure you do not come off harshly. Calmly let them know the mistakes they have made and give them a game plan of how to correct those mistakes.
By giving them a game plan of how to correct those mistakes you are showing them you have confidence that they can do better.
Keep in mind: After a bad loss you should never beat them down, you should motivate them to do better. One essential aspect of being a coach is being able to motivate your team. Losses are a big part of baseball and softball, they are going to happen. How you deal with these losses can make or break a team so make sure you handle them the appropriate way.