It looks likes AA3161 was delayed awaiting a Captain.
Yes. According to the FA the original captain was "reassigned to another flight and we had to wait for another captain."
Not to be uncharitable but pilot shortages or other operational issues are not my concern. My concern is the reliability of the product I am purchasing and AE is falling woefully short in this area of late. They are completely unreliable and it needs to be fixed. Ac agent in DEN was telling me that a number of commuters on the DEN-LAX route have moved to other carriers due to the perpetual delays on that route.