I agree with Tamara's answer. To me to rock equals to slay. I just don't think it's very used nowadays, at least I haven't encountered it much on the internet.

Many times “To rock it” or “rocking it” is slang for giving your all to whatever you happen to be doing and generating enthusiasm in others at the same time So maybe this situation means that he won't do his best at running that place

I would need more context to be certain but it sounds like they are talking about a band who are so bad they could not even please (or „rock“) a crowd at a local pub, let alone a BIG crowd.