No doubt in my mind that failure to communicate ranks right up there. This includes not putting out important information, or putting it out too late for anyone to act upon it with any measure of effectiveness; failure to communicate expectations or give proper direction - expecting subordinates to be mind-readers, then chastising them when they come up with solutions which differ from the commander's. Those are among my biggest frustrations and have continually been the most complained about things among JOs in my several commands. If you think you're communicating enough, redouble your efforts at every opportunity.
Brett
Sounds like one of my old skippers. He would stand by the duty desk and stroke his chin thoughtfully while not saying a word. 3 days later we'd hear from the OPSO about something or other we JO's did that he did not like. One of our Ground O's finally blew up about this one day saying: "We are all grown men here. If you don't like something we are doing just tell us instead of complaining to the OPSO for us to hear about it days later!"