On what basis are you claiming that? Do you have any idea about how the other CEOs before her did?
Disclaimer: I worked at Yahoo for several CEOs, including Mayer. I think she was the best CEO at Yahoo in a long time. So please, enlighten me why my impression of her is incorrect.
https://www.inc.com/geoffrey-james/top-10-management-mistake...
https://qz.com/314225/everything-we-learned-from-marissa-may...
https://www.forbes.com/sites/mikemyatt/2015/11/20/marissa-ma...
http://www.frontpagemag.com/point/262704/why-wont-anyone-tal...
http://gizmodo.com/heres-what-happened-to-all-of-marissa-may...
https://www.thestreet.com/story/13332877/1/yahoo-ceo-mayer-i...
http://variety.com/2016/digital/features/marissa-mayer-yahoo...
http://www.foxbusiness.com/features/2015/12/30/worst-ceos-20...
http://www.growthbusiness.co.uk/the-worst-ceos-in-corporate-...
https://www.entrepreneur.com/article/272469
https://www.nytimes.com/2014/12/21/magazine/what-happened-wh...
Do you want more?
I was there. I saw the sea change she brought into the company. Morale skyrocketed, after the company was just drifting around for years. Compared to Carol Bartz, she was a CEO extraordinaire.
I remember reading Eric Jackson's screeds and he was clueless as hell.