It's hard to know. If others found problems, then you're a bad self-critic. If others didn't find problems, you're a good writer, but we don't know about your critic abilities.

What I meant was really along the lines of comparing how good your self-criticism is of stuff you've written a long time ago with your criticism of others. If you're better at criticising others (my guess), then you could try to account for that deficit when comparing that to your writing ability. I don't know how far that will get you.

I agree that it can't be compared directly.