Starbucks soared as it poached Chipotle's fearless leader.It's not often that a personnel change can move a stock by double-digit percentages, but that's exactly what happened on Tuesday, when Chipotle (CMG -2.78%) CEO Brian Niccol said he was jumping ship for the top job at Starbucks (SBUX 0.53%). Chipotle stock was down 11% as of Tuesday morning, while Starbucks had jumped 21%. Altogether, Niccol's move represented close to a $30 billion swing in market cap.Niccol is rightly regarded as something of a sta ...