The first sentence requires semicolons instead of commas:
"The captains of the high-school softball team are pitcher, Marisa Martino, outfielder, Rachel Morrison, and catcher, Lisa Fiore."
This sentence lists multiple roles (pitcher, outfielder, catcher) along with their respective names, so the items in the list can be better separated by semicolons to avoid confusion. The correct format would be:
"The captains of the high-school softball team are: pitcher, Marisa Martino; outfielder, Rachel Morrison; and catcher, Lisa Fiore."