I don't think that's quite the way it's meant, at least not by those who've had a bad game [day]. to me it sounds more like, "yeah, I (or we) had a bad game [day]; <this sport [life]> is like that [hard] -- let's move on."

Could be. I've never heard it uttered by a sports person. I was just guessing.

Ceci n'est pas un seing.