I know that much, but educate me on this scenario:
Chico's on the mound, and Zimmerman makes an error to start the inning. Later in the inning, runners are on second and third with two outs. The runner on third was because of the error. Both runs score. Even though the runner on second wasn't because of error, there would have been three outs had Zimmerman made the play. Is the second run earned or unearned?
If that were a real situration, and a second run scored, that run would have also been unearned. After there would have been 3 outs if not for errors, all runs are unearned to the team. However, if a relief pitcher comes in, with two outs when there would have been 3 if not for errors, and gives up a home run, he is still charged for an earned run for the HR (any baserunners are still unearned). But, just to make things confusing, the team is not charged any ER. Every once in a while you will see that the teams total ER are less than the total of the ER of the individual pitchers. That makes a mess out of a scorecard.