After giving this some thought, I think our response has changed depending on his age.
When they are little they move on to the next thing pretty quickly.
I always keep in mind that no one feels good about performing poorly and they don't need to be reminded of it. However, there is the opportunity to learn and grow. My husband will talk to my son about it later, if he feels he has a constructive comment or something to be learned for the next time. Sometimes they just have a bad outing and nothing needs to be said.
I don't know that much about baseball , so I just give hugs and support.