As others have correctly pointed out, an increased cash balance (or a snapshot thereof) means nothing without a total breakdown and forensic audit of the balance sheet.
The accountants could be crediting payments for sold seats on future flights, sold assets that haven't left the property, payments on account for??? etc. etc. The list is endless and is easily manipulated to show the best possible scenario for a given situation at a given point in time.
Best of luck to the pilots at Delta. I have been in your shoes and it is a sickening feeling. All I can say is keep your chin up and never let this industry affect your health or your family.
In the end, those are the most important things in life.