Let's examine the case of Captain Harriman of the Enterprise-B, as seen in the first part of the movie Star Trek: Generations.
Considered against real-world captains, Captain Harriman might not look so bad. In the real world, some fights are just too hard for anyone to win. But what about in the world of Star Trek? How does Captain Harriman compare to other Star Trek captains? And in particular, how does he fare against other captains of ships named Enterprise?
In my judgment, Harriman does not measure up. At every step, he failed to do what anybody truly worthy of skippering the latest ship to bear the proud name Enterprise would have done. Let's look at the evidence.
1. When the distress call was received, a real Enterprise captain would have looked for a way to render immediate assistance. Harriman's first reaction was to look for someone else to solve the problem.
2. When it was made clear to him that it was his problem to solve, a real Enterprise captain would have welcomed the responsibility of solving the problem himself. That doesn't mean trying to be a hero; he could have asked the extraordinarily experienced Kirk for advice. But a real commander would never -- never -- have offered anybody else the Big Chair. Not even James T. Kirk.
3. So what if the press were there? In a command like that, your every action is already going to be recorded whether the press are there or not. If you're not ready for that level of scrutiny, if you're not confident that you are the right person for that job, then you're not the right person for that job.
4. So what if the ship didn't have a full complement, or wasn't fully space-ready? Nobody cares about excuses. All that matters -- all that has ever mattered, really -- is whether you did the best you could with what you had. I'd argue that that's true for any human, but I think it's pretty clearly true for Starfleet officers. How many times did Kirk save the day with a good poker face and an absolute determination not to lose? Granted, Kirk is a special case, but I expect a real Enterprise captain to at least try. By that standard, Harriman comes nowhere close to measuring up.
On balance, then, like Cadet Captain Watters, Captain Harriman may have been a good man, but -- going solely by what we saw in ST: Generations -- he was not a good Enterprise captain.
(I should add that it's clear Captain Harriman seemed unprepared to command the Ent-B solely because that's what the script required. It's unfortunate that he went down in history as "the guy who got Kirk killed," but hey, that's what happens when you allow yourself to be turned into a fictional character. :) He fares a little better, however, in the fan-produced series of short films, Star Trek: Of Gods and Men.)
(I should also add that this is in no way a criticism of Alan Ruck, the actor who has portrayed Captain Harriman. He did a fine job portraying a character who doesn't quite meet the demands of a tough situation.)