Your question seeks several answers. First, who is responsible. Your claim for the purported "false advertisement" would be against the entity who adervtised the event, and upon whose advertising you relied. That's stub hub. Unfortunately, stub hub has a host of disclaimers concerning their role in brokering tickets to multiple entertainment events. While we have had success in a class action against Ticketmaster, your potential claim against stub hub is for "damage" caused by a change in gate times by another party. Second, you ask whether there is a potential class action. Its unlikely against stub hub. As for the Athletics, they potentially have an even better defense: the disclimer on the ticket itself. Sporting events, as with most live entertainment, seek to limit their liability by disclosing on the ticket that they are only selling a "license" to see the event, revocable largely in their discretion. The bobblehead was part of a one-time promotion, which the Athletics likely disclosed was "first come, first serve." A recent class action by purchasers of Superbowl tickets denied access to the seats they bought was recently rejected. While we would like to help you, your best recourse is perhaps to contact the Athletics's promotions dept and see if they can't accomodate you, given that you made the ticket purchase for the reason you did. Good luck.
I agree with the previous post that the best recourse is informal -- a phone call to the A's guest services or something to that effect.
Under Business and Professions Code 17200 or 17500, you would need to show reliance on a material misrepresentation. In this case, it appears that the gate opening time is the issue. Unless that time was disclosed on the ticket, on Stubhub, or somewhere else, I think the case is pretty weak. Even if the gate opening time were disclosed, the bobblehead is technically a free giveaway so getting restitution under 17200 or 17500 would be dicey. I don't see this as an attractive class action.