A comparison I like to use is with studying for tests, and performance on tests.

Let's say you're applying for grad school and studying for the GRE. You study really, really, really hard, take a bunch of practice tests that say you should get a 1400, but when you actually take the exam, you only get a 1200. They just happened to ask you a bunch of stuff you weren't prepared for, maybe you were sick that day, maybe you almost got into an accident on the way to the testing center, WHO KNOWS. You just know everything was going against you and you're better than that.

If you take the test again, would you expect the second test to be closer to the 1200 you got last time, or to the 1400 you prepared for? If studying were FIP and actual test performance were ERA, you'd expect your second test to be a lot closer to 1400 than to 1200 - and almost certainly not WORSE than 1200, right?

It's sort of a philosophical question - if you're "a good pitcher" but you allow a lot of runs, does it even matter how good you are? If you study really hard for a test but you flunk it, does it matter how much you studied?