Facebook CEO Mark Zuckerberg is turning to an old friend and former Harvard teaching assistant, Andrew “Boz” Bosworth, in a time of trouble for the company.

Last week, a damaging series of reports in The Wall Street Journal showed major problems in the company’s ecosystem, including a lack of content moderators for markets outside the U.S., an avalanche of anti-vaccine misinformation in user comments, and Facebook-owned Instagram’s negative effect on teens’ mental health.

Some of the reports said Facebook employees and execs knew of these problems but could not or would not fix them. Lawmakers have already pledged to question execs from Facebook and other Big Tech companies over social media’s effects on teens.

On Wednesday, Facebook shuffled its leadership. Next year, Mike Schroepfer will step down as Facebook’s CTO after more than 8 years. He will be succeeded by Bosworth.

Schroepfer has not stated why he is leaving or if it has to do the Journal reports. In his note announcing his resignation, he said he hoped to dedicate more time to family and philanthropy while still helping out with recruiting and with artificial intelligence technologies as the company’s first senior fellow.

Zuckerberg has once more turned to Bosworth as one of his most trusted assistants.

Bosworth is Zuckerberg’s “go-to guy” since his 2006 arrival. His key products were developed and he has led the turnaround of crucial divisions such as hardware and Facebook’s bread-and-butter: advertising. His reputation is for direct communication with peers and his subordinates. He also frequently posts his thoughts on technology, leadership and personal growth — internally and on his public blog.

For a corporate executive, some of his thoughts may seem unusually direct. For instance, in a leaked memo from January 2020, Bosworth said Facebook was more like sugar than a toxin.

He said that Facebook is not nicotine but “I think it’s probably sugar.” Sugar is delicious, and most people have a place in their lives for sugar. It is best to use it in moderation, as with all things.

In a 2016 memo that leaked, he wrote about an attitude among some Facebook employees that connecting people is “de facto good” even if it sometimes leads to bad outcomes, like bullying or a “terrorist attack coordinated on our tools.” Bosworth explained to Zuckerberg that their memo was intended to critique this attitude among Facebook employees, rather than defend it.

Bosworth is also one of Facebook’s most accessible executives, posting frequently on Twitter or holding Q&A sessions on Instagram. Most recently, he launched a podcast called “Boz To The Future” where he and guests discuss the latest in technology.

The company is also divided by him. CNBC spoke to an ex-employee who requested anonymity in order not to disclose his non-disclosure agreement. He said that Bosworth believes he is a genius but has probably been lucky in his career. CNBC spoke to a former employee who was a direct manager for Bosworth and said that he is passionate about his job, demands excellence from his workers.

Facebook did not respond to our request.

Bosworth met Zuckerberg at Harvard as a teaching assistant in an artificial intelligence class. Bosworth was one of the first software engineers to join Facebook after Zuckerberg’s 2004 founding.

Bosworth made a mark in a matter of months. His contribution to the creation of what is today the most prominent Facebook feature, News Feed, was a rare software engineer. Before News Feed was launched in September 2006 there were many profiles that users could use to jump around and leave posts on other “walls”. News Feed brought together all these posts in one screen. The content never stopped coming. CNBC reported that Bosworth, an ex-executive, is considered the “godfather” of News Feed.

Initial concerns among Facebook users included the fact that all of their messages were visible to their friends. However, the feature became very popular.

Facebook became mobile-first and primarily web-focused in 2012. Zuckerberg appointed Bosworth as the head of its advertising product development. Bosworth, a former Facebook executive, said that he took over a chaotic hodgepodge of products from a division that was struggling and turned it into nearly $27Billion money-maker.

In August 2017, Facebook announced that Bosworth would manage consumer hardware, including the company’s struggling skunkworks division of Building 8.

Despite not having any experience in hardware work, Zuckerberg hired Bosworth to help fix his teams. This included Oculus’ virtual reality division, which was acquired for $2.3billion. Oculus’ first consumer headset, Rift, had just been released a year before and Building 8 wasn’t able to produce products at the rapid pace that Facebook expected.

Bosworth over the last four years has rebuilt and refocused Facebook Reality Labs’ hardware division.

The company now has an extensive range of gadgets that can be purchased. These include the Oculus Quest headset, the Portal, Portal Go, Portal+ and Portal TV video-calling devices, and smart glasses built in conjunction with Luxottica called Ray-Ban Stories. Earlier this year, Facebook also announced a new team within Reality Labs that will focus on the metaverse — a future space in virtual reality where people can meet.

Facebook is yet to release specific figures on its hardware products, but it has reported that the revenue from Workplace, Facebook’s enterprise software division has grown by nearly 118%, to almost $1.8 Billion in 2020. That’s an increase of nearly 118% over $825 M in 2018.

Zuck now turns to Bosworth for a new job, as he is in need of a crucial spot.