What: Shares of Tuesday Morning Corporation (NASDAQ:TUES) plummeted 18.75% Tuesday after the off-price retailer unexpectedly announced Michael Rouleau is retiring as the company's CEO and as a member of its board of directors, effectively immediately.

So what: Tuesday Morning didn't appoint an interim CEO, but did create a new "Office of the Chairman," led by Board Chairman Steven Becker, "to support oversight of the Company's strategic initiatives until a new CEO is appointed." Tuesday Morning also added a new lead independent director role to be held by board member Terry Burman. In addition, to aid with the transition, Rouleau will serve "in a consultative capacity" through March 31, 2016. Tuesday Morning has also secured retail executive search firm Herbert Mines Associates to evaluate permanent CEO candidates in the meantime.

Now what: That's little consolation for Tuesday Morning investors, who reacted similarly when the company's CFO resigned in July, and have endured a 75% year-to-date decline. That includes a massive 36% single-day drop last month after the company reported drastically weaker-than-expected quarterly results. To its credit, however, at least one analyst was willing to go out on a limb the following week to argue Tuesday Morning's turnaround appears to remain intact for investors with a long-term view.

Rouleau, for his part, echoed that sentiment by stating, "With Tuesday Morning's rebuilding program well under way, now is the right time to transition to new leadership. ... I am proud of what the team has accomplished over the last couple of years and believe there is still so much opportunity for Tuesday Morning."

In the end, though, this latest -- and arguably most significant -- executive departure doesn't exactly seem like a stirring vote of confidence. Until the company shows more tangible proof its turnaround is taking hold, I'm content watching Tuesday Morning stock from the sidelines.