There are also pro-sports in Oakland, which is closer than San Jose is.
A big difference between Vancouver-Seattle and Sacramento-San Jose is that Seattle will likely draw fans from Canada who can't get Canucks tickets because they are sold out. Being near Canada is a big natural advantage for Seattle.
I think Seattle is just too far from the border to make it realistic to expect many Canadian fans to go to games, especially weeknight games. Even from White Rock you are looking at 2 hrs under the best of conditions. Much more during traffic time or with heavy border traffic. For Vancouver itself, Burnaby, the North Shore, etc., even further.
Its not nearly as close as St Catherines, e.g., is to Buffalo.
Re the Bay Area, SJ doesn't draw many fans from Oak/SF, let alone Sacramento or other parts of the Central Valley. Just too far.