It's funny yet so sad, the neutrality activists kicked into high gear to defend FUTURE neutrality for poor Indians who are years away from actually having 'net access under current pricing. With Free Basics, the poor would have immediately had some 'net access, including being able to use social media and messaging at low/no cost. Now they can just sit in the mud and wait, secure in their neutral purity.
If it's not a personal/health issue, then I would guess it's a matter of not being in the MM faction, and not wanting to stay on if in complete opposition to the company's chosen direction. If you can't support the current direction and can't change it, best to bail out immediately. Directors probably don't want to just occupy a chair, especially on a sinking ship.
YHOO resembles Berkshire Hathaway when Buffett bought it in the 1960's. It was a going concern, but the market value was less than its assets (including cash). Buffett obviously didn't care to go into the textile industry per se, but simply recognized the disparity between market and book value. He basically bought the company using its own assets. The major obstacle to this is Buffett's oft-stated aversion to buying into an industry he does not understand. But he HAS bought into media (newspapers, Disney, TV). The part of YHOO that needs repair, or a piecemeal sale, is the media (and Internet) part; the rest is a holding company for BABA, Yahoo Japan, etc which Buffett could easily leverage or dispose of in some fashion.
When you read about such things, look for the words "programmed sale." People with such large positions in many companies often have tax and financial planners who make such pre-planned sales as part of the client's overall investment strategy. "Programmed" means it was going to take place regardless of price. Unless you know the particulars of the person's finances, you won't know the purpose of the sale. I have seen Andreessen's recent sales described as programmed sales, so I would not read anything positive or negative about FB into it.