Free-agent third baseman Bill Mueller is expected to choose his new employer today, and the Pirates are thought to still be the front-runner, as has been the case since they upgraded their contract offer Friday from two to three years. But that does not necessarily mean he will pick Pittsburgh. A source close to the negotiations yesterday said Mueller would decide "within 24 hours" where he will play next season and strongly suggested a desire to play on the West Coast still could have an influence. The Los Angeles Dodgers and San Francisco Giants also have made offers and have reiterated their interest in the early part of this week. Although the Mueller family maintains its offseason home in Missouri, Mueller spent parts of six seasons with the Giants, and his wife, Amy, is from San Francisco. Mueller also has longtime ties to Dodgers general manager Ned Colletti, a former assistant GM with the Giants. "But the Pirates are very much in this," the source said.