It seems what they mean when they say "improvement" is merely the stock price increasing. As that data-point is set by investors, I don't see why Zuckerberg could be at fault for this. I also don't see how a CEO who goes around projecting his self confidence to worried investors but without a good technical background would be an "improvement" over Zuckerberg, who despite all malaise towards him is a better programmer than most. Just my thoughts.

edit: I was reading the comments of the article and one of them notes that by selling the IPO at 4x of what it should have been priced, Zuck showed that he is a brilliant CEO.