After an injury to Buster Posey in May 2011, Whiteside split time catching with Chris Stewart for the rest of the year. He lost the role of backup to Héctor Sánchez in 2012 and appeared in just 12 games for the Giants during their second World Series-winning season in three years. Following 2012, Whiteside was claimed off waivers multiple times by different clubs before finally winding up with the Texas Rangers, who assigned him to their Triple-A team in 2013. In 2014, he competed for a spot on the Cubs' roster but was beaten out by John Baker and sent to the minors.