The Giants traded for Jose Guillen on August 13, 2010 and thought their right field woes had been solved as they made their playoff push. Guillen was 34 years old but having a decent season (102 OPS+) with the Royals at the time of the trade and had cleared revocable waivers earlier that August.
Still, he was old and had been bad the previous few seasons, so he was almost too perfect of a pickup for the Giants. The Padres were still 3.5 games ahead for the division lead and they needed a source of cheap power to keep pace.