confident in or about?

A fellow editor was wondering about the distinction, if any, between confident in and confident about.  This is what I make of it:

You can have confidence in a thing or person – that means you trust it. It’s other-oriented. Confidence about can be self-oriented or a more neutral assessment of likelihoods, but tends to refer to some specific assessment of probability more explicitly stated, whereas “confident in” needs no further explanation.

Say, for example, that at some point you say the Leafs won’t make it to the playoffs. At a later point, to the same person (who remembers you saying the first thing), you say

a) I’m confident about the Leafs.
or
b) I’m confident in the Leafs.

Option (a) is likely to be taken as meaning that your perspective hasn’t changed – you’re confident that the Leafs won’t make it.

Option (b) is likely to be taken as meaning that your perspective has changed, and you’re now confident that the Leafs will succeed, unless you have framed losing as a goal. (Example: “I’ve bet against the Leafs. Got big money riding on their losing. But I’m confident in them – they won’t disappoint me by accidentally winning.”)

Also consider that if you say “I’m confident in this bridge,” it may sound odd, as confidence is usally placed in something capable of being an active agent, whereas if you say “I’m confident about this bridge” without further explanation, the person you’re speaking to will likely ask for further clarification: “In what way? How so? Confident about what about it?” expecting a reply such as “I’m confident that it is the bridge we were looking for.”

The preposition is the key. In enters the object, invests it, makes it the agent; about looks at the object from outside. Compare believe in with believe about.