Welcome to the FICO Forums, tommigrrl!
FICO doesn't care one way or the other how you pay your bills, as long as they are paid on time, every time.
Automatic billpay systems are notoriously unreliable. I would guess that what happened to your coworker was that his billpay payment didn't go through for whatever reason, which caused his creditor to put a notation on his credit reports that he missed that month's payment. This could definitely cause a 30-point drop in one's score, if not more.
I would never trust any automatic billpay system to pay all of my bills on time for me. If I used one of those systems (which I don't), I would at the very least double check and triple check that each payment went through before it was due.