"Good" has always been used to describe the middle ground of "success" (between "acceptable" and "excellent"), whatever the context may be. In the scope of computer games, it's a rather complex mishmash of achieved goals, how far you've come, and comparing yourself to others. It is mostly a personal view that you have developed over the course of playing the game, so the best answer I can give you is:
If you have no idea what"good" is yet, then you probably aren't "good"... yet.
Knowing that the owc maps are very high difficulty (like those mod pools), is actually a step in the right direction of figuring out what "good" is and your post already indicates that you have an idea. But because of your lack of experience (not referring to skill), your idea was shattered because this was the first owc you saw and probably guessed this was the standard, since it was still group stages. But this year's map pool is actually much harder compared to last year and the group stages are a bit of a joke, but I kinda like it this way. It's more fun to watch.