I'm not at all surprised at the love for SJC and my experience is that in premium cabins, SJC is regularly more expensive than SFO already at some times of year (priced ex LHR anyway).

SJC is broadly a joy to fly into though - I suspect I'm driving away in my rental car before I'd even be out of the airport and on the AirTrain to the rental centre at SFO. Given equal driving time from either, I'd fly to SJC every time. It's a pretty well timed flight too in my view - slightly later than the second SFO rotation. I suspect it is something of a goldmine for BA given the loads I've seen and a lot of it is corporate travel (which is to be expected - anybody working for or with Google, Facebook, Apple or Netflix head offices for starters is going to find SJC *much* more convenient).

To be honest, I'd think if BA were looking at unnecessary alternatives then I've always struggled to understand the point of EWR...

Which raises a question - do BA have a slot for another NA route or would this be necessarily coming from removing something or reducing a frequency somewhere?