Given Chipotle's (CMG -1.63%) recent stock performance, one has to wonder if it's still reeling from the sudden departure of former CEO Brian Niccol last summer. Eight months after Scott Boatwright became the company's new CEO, the stock is now down over 25% from its high.Despite the uncertainty such a transition brings, it's not necessarily clear why the restaurant stock is suffering. Is it down because of temporary factors, or do investors need to start taking a more negative view of the company? Let's ta ...