If the Athletics move to San Jose...

...then the Giants will shift their marketing to the East Bay, and Silicon Valley companies can provide funding to support a major league team. Each Bay Area city will have have two major league sports francises. San Francisco (Giants, 49ers), Oakland (Raiders, Warriors), San Jose (Athletics, Sharks)...seems to be closely balanced.

Oakland do not have enough financing to support three major sports francises or funding for a new stadium in the area, so San Jose would be a better place to relocate.

Oakland Athletics made a stadium deal with Fremont, CA

So the Oakland Athletics are going to build a stadium in Fremont, only 12 miles away from San Jose but stil within Alameda County. They will still be Oakland Athletics despite being closer to San Jose, and it would not interfere with the Giants marketing territory.