Say what you like about Carol Bartz’s one-and-a-half-year tenure at Yahoo — good, bad, or just ho-hum — but there’s no denying that high-level executives keep leaving as the CEO streamlines the troubled tech company and attempts to transform it into a viable competitor against the likes of Google and Facebook.

Last week, Bartz confirmed in an internal memo to employees the latest wave of departures, including U.S. head Hilary Schneider. “Yes, they’re leaving, but each for different reasons that suit their life,” she wrote. While more than 15 top-ranking execs have left over the past year and a half, we tallied the most significant.

Hilary Schneider
Outgoing Executive Vice President

Schneider joined the company in 2006 and took on the EVP post in 2007, soon after former CEO Terry Semel stepped down. (At the time, Yahoo’s stock price had dropped 30% over the course of 18 months.) During her tenure, she oversaw ad sales, partnerships, and programming in North and South America.

Soon after Bartz sent out that now-famous memo, Schneider sent out one of her own. “I know that transitions can create swirl — but our customers, both consumer and marketers, are looking to us for continued leadership…and I know we can deliver this.”

Schneider has decided to stay on with the company until a replacement is found and has not announced her plans post-Yahoo. But at the very least, she’ll be compensated for the extra time: According to an SEC filing, Schneider will be paid $420,000 for her “transitional work.”

Jimmy Pitaro
Outgoing Vice President of Yahoo Media

Pitaro joined Yahoo in 2001 when the company acquired Launch Media. As VP of Media, he was the guiding force behind many of Yahoo’s properties, including News, Finance, and Sports, which as of March 2010 received more than 80 million monthly visitors combined.

Rumors of Pitaro’s departure had been hounding him for weeks – at a recent press event, Pitaro would neither confirm nor deny them — but it wasn’t until late last week that they were finally confirmed. He will be joining former Playdom CEO John Pleasants as co-president of Disney Interactive Media Group; Pitaro will run Disney online, while Pleasants supervises games.

In a statement, Disney CEO Bob Iger seemed please as punch to land Pitaro, saying, “Jimmy has vast knowledge of the online world and has been hugely successful at creating and building audiences around branded online content.”

David Ko
Outgoing Senior Vice President, Yahoo Audience, Mobile and Local businesses

The senior VP has been with Yahoo since 2000 and held various positions along the way, including vice president for Yahoo’s mobile business in Asia Pacific, where he negotiated 24 partnerships for the company in 16 months. Ko is also credited with playing a key role in the distribution strategies of Yahoo Mail and Messenger.

Bartz also confirmed Ko’s exit last week. In what many might view as a coup, Zynga announced this week that Ko is coming aboard as senior vice president of media, where responsibilities will include spearheading the company’s mobile efforts. According to All Things D, Zynga execs had been courting Ko for months, due in no small part to his experience navigating the Asian market.

Srinija Srinivasan
Former Yahoo vice president and editor-in-chief

In the mid-to-late 1990s, Srinivasan, who joined the company as its fifth employee, was considered one of the most powerful in search. Recruited by co-founders Jerry Yang and David Filo, Srinivasan played a key role in transforming Yahoo search from what was then a website directory to what, years later, we would eventually take for granted as the contemporary search engine experience. It was thanks in large part to her that Yahoo dominated web search during the late 1990s, against competition like Alta Vista, Excite, and Lycos.

“Today, more than 15 years later, I’m proud to announce my graduation from Yahoo! employee to Yahoo! user,” she wrote at the time of her resignation. “No blog post can capture the density of this experience, the richness of what I’ve learned, and the profound gratitude I’ll always have — for David and Jerry taking that leap of faith in me, and for the thousands of Yahoo! employees who have made this a place where magic happens.”

Since her departure, Srinivasan has focused on her longtime love: jazz. She is currently the chair of SFJAZZ, a San Francisco–based nonprofit, where she is developing a performance and product center for creative music in Brooklyn.

Ash Patel
Former Yahoo Executive Vice President Product Architecture & Strategy

Like Srinivasan, Patel was one of Yahoo’s first employees, joining the company before it went public in 1996. During his 14-year stint, he was responsible for global technology investments, product platform engineering, and platform strategy; Patel played a key role in the architecture and iteration of MyYahoo, Finance, Messenger, and Chat.

In November 2009, Yahoo announced Patel was taking a sabbatical to spend time with his family and would return  in early 2010. But last March, Patel announced he was leaving the company for good. As he told TechCrunch then, he was taking several months off but occasionally advising startups. Online advertising company Buysight announced Patel had joined  its board of directors last May.

Neal Sample
Former Vice President for Social Platforms

In August, Sample announced he was leaving to become eBay’s VP of architecture.

“It is with mixed emotions that I tell you that I am moving on,” he said in his staff memo. According to Sample, the decision was not an easy one, though he has not discussed specific reasons for the move.

The former VP and his team were reportedly responsible for Yahoo’s unsuccessful catch-up strategy against social network giants Facebook and Twitter, which involved managing the design and delivery of the company’s social components, as well as engineering social elements in Profiles, Mail, and the Yahoo Front Page. He was also on Yahoo’s open strategy leadership team, which enables developers to access the company’s social and data layers in its various products.