Gert Funck, is your current theory that your GK is having success on set plays because he is overall very highly rated or because you managed to pinpoint the GK skills that internally mean the same as shooting, crossing, finishing?

In your OP, you hypothesized that

Rushing out = Shooting
Communication = finishing

Was this a random guess or a specific assertion that you have since proved (or not)?

And while we are talking about your player (never mind him being a GK) having great success with set plays and pretty much my entire squad struggling, what skills do you consider crucial for CK, FK, PK?

I have always assumed:

CK = crossing
FK, PK = shooting, with finishing as tiebreaker

But some say you just have to test each player.