I'm just wondering if I really understand what auto-correlated error terms are:

Say I'm looking at time series data of the points per game scored by a basketball player.

Say he playes despite being slightly-injured during the last 10 games of the season. His points per game scored during those last 10 games are lower than during the other games of the season in which he played. They all end up being underneath the regression line/curve.

Would the 10 last data points all have error terms that are auto-correlated with one another?

another question:

Are auto-correlated error-terms always *caused* by the same thing?

If a basketball player injured his hand and then exactly at the moment when his hand was at 100% again he had a cold (yet played). Now all (or most) of those data-points should be below the regression curve. However not all of them are auto-correlated, but only those that belong to the same causation?