The Oakland Athletics have gone from the team desperately trying to leave Oakland just a few years ago to the one that will soon become the lone pro team left in the East Bay city. With the Oakland Raiders having been approved this week by the NFL to move to Las Vegas in 2020 and the NBA's Golden State Warriors set to move across the bay to San Francisco in 2019, the A's will soon have Oakland to themselves and are playing up their long connection to the city. ''When I took over as team president, I saw Oakland as a strength,'' said David Kaval, who started in his new role late last year.