Yahoo CEO Marissa Mayer has made another major move in her mission to overhaul the flagging internet company, snatching up Google Executive Henrique de Castro and appointing him as its new chief operating officer in a four-year deal reported to be worth close to $58 million.

De Castro, 47, had previously worked for Mayer as vice president of Google’s partner business solutions worldwide. With his new appointment, De Castro will oversee Yahoo’s sales and operations, the firm said in a statement.

It’s being reported that De Castro will be extremely well compensated for the move, with an annual salary of $600,000, plus stock options worth $36 million, restricted stock options worth another $20 million, and a cash bonus of $1 million as the icing on the cake.

Mayer, who is Yahoo’s fifth CEO in four years, has been ringing the changes since her appointment last July as she tries to rebuild one of the internet’s biggest fallen giants. Many of Mayer’s new measures have obviously been influenced own her time at Google. Not only is she poaching people that she’s worked with before, but she’s also adopted many of her former company’s practices at her new empire – such as free food, and redesigning cubicles and offices to make them more fun, in true Google-style.

Yahoo was one of the earliest pioneers of email and internet search, and even now it’s still one of the biggest names around the web. But recent years have seen it lose an awful lot of ground to rivals like Google, who has come to dominate search and establish themselves as the web’s most instantly recognizable company.

Mr. De Castro was quick to recognize this fact when announcing his appointment yesterday:

“This is a pivotal point in Yahoo’s history, and I believe strongly in the opportunity ahead.”

How big of an opportunity the future holds for Yahoo is open to debate however. The company’s share of US online advertising revenues have taken a massive hit in recent years, falling from 15.7% in 2009 to just 9.5% last year.

This led commentators such as GigaOM’s Om Malik to declare that Yahoo is rotten to the core, adding that Mayer doesn’t have a hope in hell of saving it, while AllThingsD’s Kara Swisher was only slightly more generous in her assessment.

SiliconANGLE’s own John Furrier was one of the few commentators more positive about Yahoo’s prospects under Mayer however. In a recent interview on News Desk, Furrier stated his belief that Mayer has what it takes to save Yahoo, although he acknowledged that the road to recovery would not be an easy one.  Furrier’s full commentary below: