I remember how much of an impatient prick and I didn't really care about this ceremony but then looking back I realize how amazing this was. Good Job Valve.
Not mediocre. She is good she just isn't a master. Im a mediocre violinist if i were to perform for some reason since ive only been playing for 1 year.
I'm not saying she's terrible - maybe "intermediate" is a better word, because she's not an "advanced" violinist - just that there are lots of better violinists available.
She is a performer. Probably one of the better fits for the job. The opening ceremony wasn't just about the music, but a show. Dota fans can now relate to her, which is why she would be better suited to a music pack than any random violinist grabbed from the Julliard school. They may perhaps play better (in music and/or game), but won't have such an apparent connection to the game or the community.